Or they purchased a new computer, or the purchased a second computer, or they want to use their registration key on a PC at school, or at work, etc.
Would they then not have the original email they were suggested to print out for later reference?
I just tested using an illegal key, it was one that said it was for 6.03, it successfully worked in 6.1, so this whole argument is simply fiction.
This you didn't need to test. A mIRC registration is a lifetime one - that's not possible if each version were to have it's own key.
