diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index e359d177..717a00de 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -2,10 +2,16 @@
 Changelog
 
 2023-xx-xx
-    Release 10.0.1
+    Release 10.1.0
 
     * Fixed `transform` with nested list #531
     * Added curl dependency in Dockerfile #532
+    * Introduce spdx_license_expression
+    * Ability to transform spdx license key from spdx_license_expression to
+      license_expression (i.e. Generate attribution with
+      spdx_license_expression) #513
+    * Ability to configure the proxy settings #533
+    * Fixed licenses issue #534
 
 2023-08-20
     Release 10.0.0
diff --git a/docs/source/reference.rst b/docs/source/reference.rst
index 48765718..3660bec8 100644
--- a/docs/source/reference.rst
+++ b/docs/source/reference.rst
@@ -83,8 +83,8 @@ Options
 Purpose
 -------
 
-Generate an attribution file which contains license information
-from the INPUT along with the license text.
+Generate an attribution file which contains license information from the INPUT
+along with the license text.
 
 Assume the following:
 
@@ -421,6 +421,60 @@ Details
                     This option tells the tool to show all errors found.
                     The default behavior will only show 'CRITICAL', 'ERROR', and 'WARNING'
 
+Special Notes
+-------------
+If the input contains values for license_file, the tool will attempt to
+associate the license_file with the corresponding license_key.
+
+sample.csv
+
++----------------+------+---------------------+--------------+
+| about_resource | name | license_expression  | license_file |
++================+======+=====================+==============+
+| /project/test.c| test.c | mit AND custom    | custom.txt   |
++----------------+------+---------------------+--------------+
+
+If the user does not utilize the **--fetch-license** option, the input will
+contain two license keys and one license file. In this scenario, the tool cannot
+determine which license key the license file is referencing. As a result, the
+license_file will be saved separately.
+
+i.e.
+
+        ..  code-block:: none
+
+                about_resource: test.c
+                name: test.c
+                license_expression: mit AND custom
+                licenses:
+                  - key: mit
+                    name: mit
+                  - key: custom
+                    name: custom
+                  - file: custom.txt
+
+On the other hand, if the user generates ABOUT files using the
+**--fetch-license** option, the MIT license will be retrieved. This will result
+in having one license key and one license file. In such cases, the tool will
+consider it a successful match.
+
+i.e.
+
+        ..  code-block:: none
+
+                about_resource: test.c
+                name: test.c
+                license_expression: mit AND custom
+                licenses:
+                  - key: mit
+                    name: MIT License
+                    file: mit.LICENSE
+                    url: https://scancode-licensedb.aboutcode.org/mit.LICENSE
+                    spdx_license_key: MIT
+                  - key: custom
+                    name: custom
+                    file: custom.txt
+
 gen_license
 ===========
 
@@ -780,3 +834,20 @@ version 32.0.0 or later. If you are using an earlier version of Scancode Toolkit
 specifically version 31 or older, it will only be compatible with prior versions
 of AboutCode Toolkit.
 
+
+Configure proxy
+---------------
+The `requests` library is used since AboutCode Toolkit version 10.1.0. To do the
+http request, users can set the standard environment variables **http_proxy**,
+**https_proxy**, **no_proxy**, **all_proxy** with the export statement
+
+i.e.
+
+        ..  code-block:: none
+
+                $ export HTTP_PROXY="http://10.10.1.10:3128"
+                $ export HTTPS_PROXY="http://10.10.1.10:1080"
+                $ export ALL_PROXY="socks5://10.10.1.10:3434"
+
+See https://requests.readthedocs.io/en/latest/user/advanced/#proxies for
+references
diff --git a/src/attributecode/attrib.py b/src/attributecode/attrib.py
index 48a61095..6c0207a7 100644
--- a/src/attributecode/attrib.py
+++ b/src/attributecode/attrib.py
@@ -323,7 +323,7 @@ def generate_and_save(abouts, is_about_input, license_dict, output_location, sca
     )
 
     if rendering_error:
-        errors.extend(rendering_error)
+        errors.append(rendering_error)
 
     if rendered:
         output_location = add_unc(output_location)
diff --git a/src/attributecode/model.py b/src/attributecode/model.py
index 13d97ab2..0ea0ae6d 100644
--- a/src/attributecode/model.py
+++ b/src/attributecode/model.py
@@ -55,6 +55,7 @@
 from attributecode.util import csv
 from attributecode.util import file_fields
 from attributecode.util import filter_errors
+from attributecode.util import get_spdx_key_and_lic_key_from_licdb
 from attributecode.util import is_valid_name
 from attributecode.util import on_windows
 from attributecode.util import norm
@@ -802,6 +803,7 @@ def set_standard_fields(self):
             ('license_name', ListField()),
             ('license_file', FileTextField()),
             ('license_url', UrlListField()),
+            ('spdx_license_expression', StringField()),
             ('spdx_license_key', ListField()),
             ('copyright', StringField()),
             ('notice_file', FileTextField()),
@@ -1222,6 +1224,13 @@ def dumps(self, licenses_dict=None):
             else:
                 if field.value:
                     data[field.name] = field.value
+        # If there is no license_key value, parse the license_expression
+        # and get the parsed license key
+        if 'license_expression' in data:
+            if not license_key and data['license_expression']:
+                _spec_char, lic_list = parse_license_expression(
+                    data['license_expression'])
+                license_key = lic_list
 
         # Group the same license information in a list
         # This `licenses_dict` is a dictionary with license key as the key and the
@@ -1244,20 +1253,35 @@ def dumps(self, licenses_dict=None):
                     lic_dict['spdx_license_key'] = spdx_lic_key
 
                 # Remove the license information if it has been handled
-                lic_key_copy.remove(lic_key)
-                if lic_name in license_name:
-                    license_name.remove(lic_name)
-                if lic_url in license_url:
-                    license_url.remove(lic_url)
-                if lic_filename in license_file:
-                    license_file.remove(lic_filename)
-                if spdx_lic_key in spdx_license_key:
-                    spdx_license_key.remove(spdx_lic_key)
-                lic_dict_list.append(lic_dict)
+                # The following condition is to check if license information
+                # has been fetched, the license key is invalid or custom if
+                # no value for lic_name
+                if lic_name:
+                    lic_key_copy.remove(lic_key)
+                    if lic_name in license_name:
+                        license_name.remove(lic_name)
+                    if lic_url in license_url:
+                        license_url.remove(lic_url)
+                    if lic_filename in license_file:
+                        license_file.remove(lic_filename)
+                    if spdx_lic_key in spdx_license_key:
+                        spdx_license_key.remove(spdx_lic_key)
+                    lic_dict_list.append(lic_dict)
 
         # Handle license information that have not been handled.
-        license_group = list(zip_longest(
-            lic_key_copy, license_name, license_file, license_url, spdx_license_key))
+        # If the len of the lic_key is the same as the lic_file, the tool should
+        # assume the lic_file (custom license) is referring this specific lic_key
+        # otherwise, the tool shouldn't group them
+        if len(lic_key_copy) == len(license_file):
+            license_group = list(zip_longest(
+                lic_key_copy, license_name, license_file, license_url, spdx_license_key))
+        else:
+            license_group = list(zip_longest(
+                lic_key_copy, license_name, [], license_url, spdx_license_key))
+            # Add the unhandled_lic_file if any
+            if license_file:
+                for lic_file in license_file:
+                    license_group.append((None, None, lic_file, None, None))
 
         for lic_group in license_group:
             lic_dict = {}
@@ -1278,15 +1302,15 @@ def dumps(self, licenses_dict=None):
             lic_dict_list.append(lic_dict)
 
         # Format the license information in the same order of the license expression
-        if license_key:
-            for key in license_key:
-                for lic_dict in lic_dict_list:
-                    if key == lic_dict['key']:
-                        data.setdefault('licenses', []).append(lic_dict)
-                        break
-        else:
+        for key in license_key:
             for lic_dict in lic_dict_list:
-                data.setdefault('licenses', []).append(lic_dict)
+                if key == lic_dict['key']:
+                    data.setdefault('licenses', []).append(lic_dict)
+                    lic_dict_list.remove(lic_dict)
+                    break
+
+        for lic_dict in lic_dict_list:
+            data.setdefault('licenses', []).append(lic_dict)
 
         return saneyaml.dump(data)
 
@@ -1764,6 +1788,7 @@ def pre_process_and_fetch_license_dict(abouts, from_check=False, api_url=None, a
     if errors:
         return key_text_dict, errors
 
+    spdx_sclickey_dict = get_spdx_key_and_lic_key_from_licdb()
     for about in abouts:
         # No need to go through all the about objects if '--api_key' is invalid
         auth_error = Error(
@@ -1779,6 +1804,27 @@ def pre_process_and_fetch_license_dict(abouts, from_check=False, api_url=None, a
             about.license_expression.value = lic_exp
             about.license_expression.present = True
 
+        if not about.license_expression.value and about.spdx_license_expression.value:
+            lic_exp_value = ""
+            special_char_in_expression, lic_list = parse_license_expression(
+                about.spdx_license_expression.value)
+            if special_char_in_expression:
+                msg = (about.about_file_path + u": The following character(s) cannot be in the spdx_license_expression: " +
+                       str(special_char_in_expression))
+                errors.append(Error(ERROR, msg))
+            else:
+                spdx_lic_exp_segment = about.spdx_license_expression.value.split()
+                for spdx_lic_key in spdx_lic_exp_segment:
+                    if lic_exp_value:
+                        lic_exp_value = lic_exp_value + " " + convert_spdx_expression_to_lic_expression(
+                            spdx_lic_key, spdx_sclickey_dict)
+                    else:
+                        lic_exp_value = convert_spdx_expression_to_lic_expression(
+                            spdx_lic_key, spdx_sclickey_dict)
+                if lic_exp_value:
+                    about.license_expression.value = lic_exp_value
+                    about.license_expression.present = True
+
         if about.license_expression.value:
             special_char_in_expression, lic_list = parse_license_expression(
                 about.license_expression.value)
@@ -1855,6 +1901,30 @@ def pre_process_and_fetch_license_dict(abouts, from_check=False, api_url=None, a
     return key_text_dict, errors
 
 
+def convert_spdx_expression_to_lic_expression(spdx_key, spdx_lic_dict):
+    """
+    Translate the spdx_license_expression to license_expression and return
+    errors if spdx_license_key is not matched
+    """
+    value = ""
+    if spdx_key in spdx_lic_dict:
+        value = spdx_lic_dict[spdx_key]
+    else:
+        if spdx_key.startswith('('):
+            mod_key = spdx_key.partition('(')[2]
+            value = '(' + \
+                convert_spdx_expression_to_lic_expression(
+                    mod_key, spdx_lic_dict)
+        elif spdx_key.endswith(')'):
+            mod_key = spdx_key.rpartition(')')[0]
+            value = convert_spdx_expression_to_lic_expression(
+                mod_key, spdx_lic_dict) + ')'
+        else:
+            # This can be operator or key that don't have match
+            value = spdx_key
+    return value
+
+
 def parse_license_expression(lic_expression):
     licensing = Licensing()
     lic_list = []
diff --git a/src/attributecode/util.py b/src/attributecode/util.py
index 45919d66..c87167f5 100644
--- a/src/attributecode/util.py
+++ b/src/attributecode/util.py
@@ -192,6 +192,50 @@ def norm(p):
     return p
 
 
+def get_spdx_key_and_lic_key_from_licdb():
+    """
+    Return a dictionary list that fetch all licenses from licenseDB. The
+    "spdx_license_key" will be the key of the dictionary and the "license_key"
+    will be the value of the directionary
+    """
+    import requests
+    lic_dict = dict()
+
+    # URL of the license index
+    url = "https://scancode-licensedb.aboutcode.org/index.json"
+
+    """
+    Sample of one of the license in the index.json
+    {
+        "license_key": "bsd-new",
+        "category": "Permissive",
+        "spdx_license_key": "BSD-3-Clause",
+        "other_spdx_license_keys": [
+        "LicenseRef-scancode-libzip"
+        ],
+        "is_exception": false,
+        "is_deprecated": false,
+        "json": "bsd-new.json",
+        "yaml": "bsd-new.yml",
+        "html": "bsd-new.html",
+        "license": "bsd-new.LICENSE"
+    },
+    """
+    response = requests.get(url)
+    # Check if the request was successful (status code 200)
+    if response.status_code == 200:
+        # Retrieve the JSON data from the response
+        licenses_index = response.json()
+
+        for license in licenses_index:
+            lic_dict[license['spdx_license_key']] = license['license_key']
+            if license['other_spdx_license_keys']:
+                for other_spdx in license['other_spdx_license_keys']:
+                    lic_dict[other_spdx] = license['license_key']
+
+    return lic_dict
+
+
 def get_relative_path(base_loc, full_loc):
     """
     Return a posix path for a given full location relative to a base location.
diff --git a/tests/test_gen.py b/tests/test_gen.py
index 06a1ea38..6feeef71 100644
--- a/tests/test_gen.py
+++ b/tests/test_gen.py
@@ -32,13 +32,15 @@ class GenTest(unittest.TestCase):
 
     def test_check_duplicated_columns(self):
         test_file = get_test_loc('test_gen/dup_keys.csv')
-        expected = [Error(ERROR, 'Duplicated column name(s): copyright with copyright\nPlease correct the input and re-run.')]
+        expected = [Error(
+            ERROR, 'Duplicated column name(s): copyright with copyright\nPlease correct the input and re-run.')]
         result = gen.check_duplicated_columns(test_file)
         assert expected == result
 
     def test_check_duplicated_columns_handles_lower_upper_case(self):
         test_file = get_test_loc('test_gen/dup_keys_with_diff_case.csv')
-        expected = [Error(ERROR, 'Duplicated column name(s): copyright with Copyright\nPlease correct the input and re-run.')]
+        expected = [Error(
+            ERROR, 'Duplicated column name(s): copyright with Copyright\nPlease correct the input and re-run.')]
         result = gen.check_duplicated_columns(test_file)
         assert expected == result
 
@@ -47,15 +49,17 @@ def test_check_duplicated_about_resource(self):
         arp1 = '/test/test.c'
         arp2 = '/test/tmp/test.c'
         expected = Error(CRITICAL,
-                  "The input has duplicated values in 'about_resource' field: " + arp1)
+                         "The input has duplicated values in 'about_resource' field: " + arp1)
         result1 = gen.check_duplicated_about_resource(arp1, arp_list)
         result2 = gen.check_duplicated_about_resource(arp2, arp_list)
         assert result1 == expected
         assert result2 == ''
 
     def test_check_newline_in_file_field(self):
-        test_dict1 = {'about_resource': '/test/test.c', 'name': 'test.c', 'notice_file': 'NOTICE\nNOTICE2'}
-        test_dict2 = {'about_resource': '/test/test.c', 'name': 'test.c', 'notice_file': 'NOTICE, NOTICE2'}
+        test_dict1 = {'about_resource': '/test/test.c',
+                      'name': 'test.c', 'notice_file': 'NOTICE\nNOTICE2'}
+        test_dict2 = {'about_resource': '/test/test.c',
+                      'name': 'test.c', 'notice_file': 'NOTICE, NOTICE2'}
         expected = [
             Error(CRITICAL,
                   "New line character detected in 'notice_file' for '/test/test.c' which is not supported."
@@ -69,7 +73,7 @@ def test_check_about_resource_filename(self):
         arp1 = '/test/t@est.c'
         arp2 = '/test/t|est.c'
         msg = ("Invalid characters present in 'about_resource' "
-                   "field: " + arp2)
+               "field: " + arp2)
         expected2 = Error(ERROR, msg)
         result1 = gen.check_about_resource_filename(arp1)
         result2 = gen.check_about_resource_filename(arp2)
@@ -85,7 +89,7 @@ def test_load_inventory(self):
         assert len(errors) == expected_num_errors
 
         expected = (
-'''about_resource: .
+            '''about_resource: .
 name: AboutCode
 version: 0.11.0
 description: |
@@ -103,8 +107,10 @@ def test_load_inventory_without_about_resource(self):
         location = get_test_loc('test_gen/inv_no_about_resource.csv')
         base_dir = get_temp_dir()
         from_attrib = False
-        errors, abouts = gen.load_inventory(location, base_dir=base_dir, from_attrib=from_attrib)
-        expected_error = [Error(CRITICAL,  "The essential field 'about_resource' is not found in the <input>")]
+        errors, abouts = gen.load_inventory(
+            location, base_dir=base_dir, from_attrib=from_attrib)
+        expected_error = [Error(
+            CRITICAL,  "The essential field 'about_resource' is not found in the <input>")]
 
         assert errors == expected_error
         assert abouts == []
@@ -113,16 +119,20 @@ def test_load_inventory_without_about_resource_from_attrib(self):
         location = get_test_loc('test_gen/inv_no_about_resource.csv')
         base_dir = get_temp_dir()
         from_attrib = True
-        errors, abouts = gen.load_inventory(location, base_dir=base_dir, from_attrib=from_attrib)
+        errors, abouts = gen.load_inventory(
+            location, base_dir=base_dir, from_attrib=from_attrib)
 
         expected_num_errors = 0
         assert len(errors) == expected_num_errors
 
         expected = (
-'''about_resource: .
+            '''about_resource: .
 name: AboutCode
 version: 0.11.0
 license_expression: apache-2.0
+licenses:
+  - key: apache-2.0
+    name: apache-2.0
 '''
         )
         result = [a.dumps() for a in abouts]
@@ -133,7 +143,8 @@ def test_load_inventory_with_errors(self):
         base_dir = get_temp_dir()
         errors, abouts = gen.load_inventory(location, base_dir=base_dir)
         expected_errors = [
-            Error(WARNING, "Field name: ['confirmed copyright'] contains illegal name characters (or empty spaces) and is ignored."),
+            Error(
+                WARNING, "Field name: ['confirmed copyright'] contains illegal name characters (or empty spaces) and is ignored."),
             Error(INFO, 'Field about_resource: Path'),
             Error(INFO, "Field ['resource', 'test'] is a custom field.")
         ]
@@ -173,7 +184,6 @@ def test_load_inventory_simple_xlsx(self):
         assert abouts[0].license_expression.value == 'bsd-new and mit'
         assert abouts[1].license_expression.value == 'mit'
 
-
     def test_load_scancode_json(self):
         location = get_test_loc('test_gen/load/clean-text-0.3.0-lceupi.json')
         inventory = gen.load_scancode_json(location)
@@ -192,9 +202,9 @@ def test_load_scancode_json(self):
         # We will only check the first element in the inventory list
         assert inventory[0] == expected
 
-
     def test_generation_dir_endswith_space(self):
-        location = get_test_loc('test_gen/inventory/complex/about_file_path_dir_endswith_space.csv')
+        location = get_test_loc(
+            'test_gen/inventory/complex/about_file_path_dir_endswith_space.csv')
         base_dir = get_temp_dir()
         errors, _abouts = gen.generate(location, base_dir)
         expected_errors_msg1 = 'contains directory name ends with spaces which is not allowed. Generation skipped.'
@@ -248,7 +258,7 @@ def test_generate(self):
 
         result = [a.dumps() for a in abouts][0]
         expected = (
-'''about_resource: .
+            '''about_resource: .
 name: AboutCode
 version: 0.11.0
 description: |
@@ -269,7 +279,7 @@ def test_generate_multi_lic_issue_443(self):
 
         result = [a.dumps() for a in abouts][0]
         expected = (
-'''about_resource: test
+            '''about_resource: test
 name: test
 version: '1.5'
 licenses:
@@ -294,7 +304,7 @@ def test_generate_multi_lic_issue_444(self):
 
         result = [a.dumps() for a in abouts][0]
         expected = (
-'''about_resource: test.c
+            '''about_resource: test.c
 name: test.c
 licenses:
   - key: License1
@@ -305,35 +315,83 @@ def test_generate_multi_lic_issue_444(self):
         assert expected == result
 
     def test_generate_license_key_with_custom_file_450_no_fetch(self):
-        location = get_test_loc('test_gen/lic_issue_450/custom_and_valid_lic_key_with_file.csv')
+        location = get_test_loc(
+            'test_gen/lic_issue_450/custom_and_valid_lic_key_with_file.csv')
         base_dir = get_temp_dir()
 
         errors, abouts = gen.generate(location, base_dir)
 
         result = [a.dumps() for a in abouts][0]
         expected = (
-'''about_resource: test.c
+            '''about_resource: test.c
 name: test.c
 license_expression: mit AND custom
 licenses:
+  - key: mit
+    name: mit
+  - key: custom
+    name: custom
   - file: custom.txt
 '''
         )
         assert expected == result
 
+    def test_generate_with_no_license_key_custom_lic_file(self):
+        location = get_test_loc(
+            'test_gen/lic_key_custom_lic_file/no_lic_key_with_custom_lic_file.csv')
+        base_dir = get_temp_dir()
+
+        errors, abouts = gen.generate(location, base_dir)
+
+        # The first row from the test file
+        a = abouts[0]
+        result1 = a.dumps()
+
+        expected1 = (
+            '''about_resource: test.c
+name: test.c
+licenses:
+  - file: custom.txt
+'''
+        )
+        assert expected1 == result1
+
+    def test_generate_with_license_key_custom_lic_file(self):
+        location = get_test_loc(
+            'test_gen/lic_key_custom_lic_file/lic_key_with_custom_lic_file.csv')
+        base_dir = get_temp_dir()
+
+        errors, abouts = gen.generate(location, base_dir)
+
+        # The first row from the test file
+        a = abouts[0]
+        result1 = a.dumps()
+
+        expected1 = (
+            '''about_resource: test.c
+name: test.c
+license_expression: custom
+licenses:
+  - key: custom
+    name: custom
+    file: custom.txt
+'''
+        )
+        assert expected1 == result1
 
     def test_generate_license_key_with_custom_file_450_with_fetch_with_order(self):
-        location = get_test_loc('test_gen/lic_issue_450/custom_and_valid_lic_key_with_file.csv')
+        location = get_test_loc(
+            'test_gen/lic_issue_450/custom_and_valid_lic_key_with_file.csv')
         base_dir = get_temp_dir()
 
         errors, abouts = gen.generate(location, base_dir)
 
         lic_dict = {u'mit': [u'MIT License',
-                                       u'mit.LICENSE',
-                                       u'This component is released under MIT License.',
-                                       u'https://enterprise.dejacode.com/urn/?urn=urn:dje:license:mit',
-                                       u'mit'
-                                       ]}
+                             u'mit.LICENSE',
+                             u'This component is released under MIT License.',
+                             u'https://enterprise.dejacode.com/urn/?urn=urn:dje:license:mit',
+                             u'mit'
+                             ]}
         # The first row from the test file
         a = abouts[0]
         a.license_key.value.append('mit')
@@ -346,7 +404,7 @@ def test_generate_license_key_with_custom_file_450_with_fetch_with_order(self):
         result2 = b.dumps(lic_dict)
 
         expected1 = (
-'''about_resource: test.c
+            '''about_resource: test.c
 name: test.c
 license_expression: mit AND custom
 licenses:
@@ -362,7 +420,7 @@ def test_generate_license_key_with_custom_file_450_with_fetch_with_order(self):
         )
 
         expected2 = (
-'''about_resource: test.h
+            '''about_resource: test.h
 name: test.h
 license_expression: custom AND mit
 licenses:
diff --git a/tests/testdata/test_gen/lic_key_custom_lic_file/lic_key_with_custom_lic_file.csv b/tests/testdata/test_gen/lic_key_custom_lic_file/lic_key_with_custom_lic_file.csv
new file mode 100644
index 00000000..16f113e9
--- /dev/null
+++ b/tests/testdata/test_gen/lic_key_custom_lic_file/lic_key_with_custom_lic_file.csv
@@ -0,0 +1,2 @@
+about_resource,name,license_expression,license_file
+test.c,test.c,custom,custom.txt
diff --git a/tests/testdata/test_gen/lic_key_custom_lic_file/no_lic_key_with_custom_lic_file.csv b/tests/testdata/test_gen/lic_key_custom_lic_file/no_lic_key_with_custom_lic_file.csv
new file mode 100644
index 00000000..d36c6304
--- /dev/null
+++ b/tests/testdata/test_gen/lic_key_custom_lic_file/no_lic_key_with_custom_lic_file.csv
@@ -0,0 +1,2 @@
+about_resource,name,license_expression,license_file
+test.c,test.c,,custom.txt