Final Cut Upgrade Issue HELP!

Mac remembering sofware serial HELP!

Hello everyone, I am in film school and my school gave everyone a academic version of final cut now I have finally saved up enough money to get the non academic version of studio 2. I uninstalled the academic version but when I install the non academic version it remembers the serial number from the academic version and installs it as a academic version because the serial is only for academic versions i guess. It never even gives me a chance to enter the proper serial number. How do I install this new copy of Final Cut with out having the mac automatically enter in the old serial number? Thanks!

How are you uninstalling it, because every time I have re-installed it, it has requested the software key.

I use appzapper I just drag the icon from the applications folder into it and zap everything it finds