So, for some reason, I didn't even think it would be a problem using my Windows 7 disc - the one I used on my PC at work. I didn't think i would have a problem using the same disk, but i believe I only have 30 days to use a product key! ahh, i already installed software and loaded drivers. What happens after 30 days? Also, can I just buy a product key and not have to reformat?
I think it becomes not genuine. The OS basically becomes nagware at that point but at least it still functions. That happened to my dad even after he had a physical retail box and a key from it entered. He had to call in which seems crazy that that was even needed with a completely legal retail box.
And yeah in the control panel/systems tab, there's a place at the bottom that usually tells you about your product key and type etc., this is where you would enter a new key.