If you are concerned with reactivation, you have 6 activations for each order so, even if you don't Deactivate ( with the appropriate button in the FSDT Installer ), it shouldn't be a problem and, using the Self-help site, you can even Deactivate something AFTER you disposed/reformatted a PC, so you can reclaim all your activations anew.
Reinstalling is instead completely unrelated to activation or license. You can install/uninstall an unlimited number of times, it won't affect activation in any way.
