No license file

[Maniues]

Please add MIT License file.
You should also add licenses from third-party code.

The best way is to add one LICENSE file with additional copyright line to LICENSE file (e.g. under your copyright line):
Copyright (c) 2019 OpenAI

Note that model.py and train.py files come from gpt-2 repos (OpenAI and fork of it) and your use of these files are under MIT license. Later, these files was relicensed under modified MIT, so now they are dual-licensed. But you can just add the above copyright line to LICENSE file.

This is not a legal advice