What exactly is your problem? You should by now have the new license key.... doesn't it work?
Sorry, I did not want to cause confusion. I have no actual problem, because I'm not the original poster (Paul B).
I believe most software publishers operate registration schemes.
Yes, many have, but the level of inconvenience it causes for the customers varies.
Registration that is bound to the current PC hardware will need updating the registration sooner or later, e.g. due to hardware changes or even reinstall on the same machine, causing extra work for you and the user.
It would get even worse if your company should be no longer available (in the best case because you got rich by selling it), then the user would no longer be able to use the program without applying a dubious and potentially dangerous crack.
My old PFE version still works with the CD key (and a combination of email address and code for the voice package), so I was able to reinstall it easily when switching from Windows XP to Windows 7.
The only other ATC software at the time I bought PFE that is usable without voice input (RC) would require an updated registration in this (and too many other) situation(s), which is one of the reasons (maybe the most important reason) I decided against it.