Please refer to this other post where @andrew_bowman explains that there's isn't a software check for a license file but it's a business issue to ensure that they have a proper license. Where does Enterprise license go in AWS instance? - #2 by andrew.bowman
Common practice and I hope they don't change from this. I know when I was using Oracle, there's not a license file but Oracle would periodically come and do an audit of our systems to ensure we were within in our licensing agreements.