Never upgrade when you're not sure...
I have (had) a registered version of Winzip 11. No problems with it, but thought upgrading was worth it. Not sure whether I was "allowed" to upgrade, so downloaded a copy of the latest version and dropped it into a different folder.
Then, of course, the new version asks me to register. Not being sure what was what, I tried my old registration code (gleaned from the help screen on the other version of winzip). Didn't work of course. Do I want to carry on with a trial? Click yes.
Only now my registered version of WinZip is no longer registered.
And, of course, I haven't got a note of the registration key. And neither has WinZip.....