Hi @mccain,
Welcome to our community, and thank you for your questions! 
Ben and Rick allow you to use their code, their assets and their concepts in your commercial games. However, it might be that they use third-party assets in some of their projects. For example, in Argon Assault, they download assets from the Unity Asset store. They cannot give you any permission to use those assets, only the creators can. For this reason, check the licences to see whether you are allowed to use certain assets in commercial games.
If in doubt, replace the assets with your own or with free assets.
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