Well, that's the objetive of the Key (or dongle, or keylock, or whatever you call it): If you have the right key connected to the parallel or USB port then the software runs, if not, you cannot use the software.
So, you need to get the source code to remove the programmed calls to the key.
Try to look at Valkyrie (decompiler) (there is a discussion about it somewhere in this forum).
Unfortunnatly, a program protected with hardware it's very difficult to break appart, unless you have the source.