It's difficult because game-devs rely heavily on good reviews. Even if you revoke a key that you know for a fact has been stolen (or bought and charged back on

It's difficult because game-devs rely heavily on good reviews. Even if you revoke a key that you know for a fact has been stolen (or bought and charged back on CC), if it has been resold there is a very good chance that the new buyer will leave you a bad review. It's a lose-lose really.