No, usually it's a combination of upgrades done simultaneously withing X amount of time that will trigger a reactivation.
Reactivation is easy however, I've done it like 5 or 6 times down on 2 desktops and a tablet PC. Just call up the number that pops up on screen (toll free in the US), speak the numbers on the screen, then type the numbers the computer on the other end of the phone tells you and you're done. Takes me 5 mins or less whenever I do it usually.
Regards,
SB