The project is clearly licensed under the BSD License. See the LICENSE file and the in-file comments below. You can't both license under the standard BSD License and carve out commercial usage.

""" authlib ~~~~~~~

    The ultimate Python library in building OAuth 1.0, OAuth 2.0 and OpenID
    Connect clients and providers. It covers from low level specification
    implementation to high level framework integrations.

    :copyright: (c) 2017 by Hsiaoming Yang.
    :license: BSD, see LICENSE for more details.

"""