Why don't they just revoke any fraudulently purchased licenses and then refund the money to the owner of the original account?
That seems like the sensible thing to do.
EDIT:
Further idea: For any purchased game, require the buyer to go online twice. Once at the time of purchase, and once after a week (or whatever), and simply deactivate the game automatically after the set period is up until the console goes online again, at which time the license is either made permanent or revoked, if the purchase was fraudulent. So temp license for a week, permanent license afterwards.
That seems like the sensible thing to do.
EDIT:
Further idea: For any purchased game, require the buyer to go online twice. Once at the time of purchase, and once after a week (or whatever), and simply deactivate the game automatically after the set period is up until the console goes online again, at which time the license is either made permanent or revoked, if the purchase was fraudulent. So temp license for a week, permanent license afterwards.