If I would investigate some time into my Idea of the "Ultimate Client Protection"... I might be able to make a client (if cracked) completly useless.
Also I know this can be bypassed, but its heavily time consuming, would take arround 2-4hrs to restore the client. (maybe if lucky enough the reverser will not even be able to fully restore it.)
EDIT: Have investigated on this Idea, works flawless and with some minor improvements and ideas it will be (*almost*) impossible to fully restore a client back to its original state. Sadly *I will never* publish it nor anymore talk bout it.