I have uninstalled and reinstalled FSX numerous times and have not yet experienced any activation key issues with either FSX or my various addons. If I understand your question, the answer is yes. sorry if this counts as hardware related i just don't have much time to post and am really curious/worried about this so i want to make sure before purchasing addons.

Sorry if it sounds confusing im just worried if i spend all the money on addons on my current product key it wont work on a new product key after uninstall on this one.

What i am asking is i lost my product key for my current fsx but if i get addons and install them to it then one day get a new pc uninstall everything get a new fsx then re install all my addons on the new pc and new fsx it should work because i uninstalled from old fsx and pc right?