If you are saving keys over reboots to gain multiple uses out of keys that are only intended to be used once then this is abuse. We have made all keys NORENT to take them away from you when you rent (if you run into keys that can still be rented please mail me).
When you do something that is unintended, and obviously unintended it is abuse. It is in your best interest to break keys when you use them.
In this circumstance, we are going to assume ulterior motives when we find a player with a lot of keys after a reboot, and punish them through 5 QPs per key and 1 level per key. Do us a favor and break your keys. Until there is a fix know that this punishment scales.