Reactivate NAV 12 ?

I recently encountered the 'Could not load scan engine" problem (link), so I uninstalled NAV and downloaded a 30-day Trial Version. I already used the SUDO command to remove the keychain and restarted.

According to this forum, I then have to reactivate NAV, but how do I do this ? I guess I'm supposed to enter the Product Key from my purchased version somewhere, but I can't find where exactly.

Any help would be greatly appreciated.

Greetings,
Wim

 

Norton Antivirus 12.3
Mac OS X 10.7