or you could just count all the bans here
There have been ~1,740 bans since key registration was required and another 4,460 from the olden times.
How many key revokes?
1240 keys have been deactivated out of 80469. The vast majority had some payment issue, either a delayed failed transaction, chargeback, paypal dispute, refund or duplicate purchase.
How many keys have been deactivated since you first released the game?