I just re-read the email from the developer after this happened to me in February - when I last reinstalled XP Pro on my desktop computer - and saw this little gem in there:
It is planned that this key file will work with all future versions of
PS Tray Factory. Should any changes be required,
I'll provide you with a new key file (free of charge, of course).
If you lose your key file and need to re-install PS Tray Factory, just
drop a note to email@example.com and I'll send it to you again.
So it would appear that the problem I encountered back then should not happen anymore! (I think I already knew that from reading that in February, but I was only remembering the problem I had leading to this email!)
Cool! I stand corrected, reprimanded, and properly back in my place! - Well, it actually was
correct info at the time of my issues with it.
But I should have been positive in my assertion, that it was still an issue. It is not!