I formatted my computer after registering nebula for the first time and installed using the setup file. I think the upgrade wouldn't work because it needs certain files only installed with setup. beware though, my first license wasn't valid anymore after I reinstalled windows. I had to submit a new .ser file and use my second license. If I ever reformat and the system blocks me from obtaining a new license I'll just email tech support and explain, shouldn't be a big deal.