They don't. But if you get big and along the way in a throwaway comment on Patreon mentioned you use the Adobe Suite and other tools they'll look into that and if you don't pay they'll send a very stern letter demanding payment.

Generally for Joe Schmo if they're found out it stops at a letter demanding payment, and if you don't pay it likely won't escalate, especially if you deny the accusation. But for someone making a profit they'll get their money and it's a major headache and just not worth it considering you are making money far exceeding the rather small cost.