Hello. So my friend has a laptop that came with Windows 7 preinstalled and was upgraded to Windows 8 Pro. I kinda doubt that he paid for Windows 8 (this was before 8.1) and the fact that it's Pro is a red flag for me. But it seems to be legit - I see no cracks or loaders installed, no KMS stuff, key is from the retail channel, nothing shows up when I google the key. It seems legit to me, but just to make sure he doesn't run into any trouble when reinstalling, I want to know how to be 100% sure that a Windows product key is 100% legit.
just call microsoft and someone will check it against their database, and then he will say if legit or not
yeah, there isn't a program that will show if a retail key is good or not. Anything out there now will just show its valid as a key. Call MS and check, Hey yo, wassup
If you don't have reciept or some kind of proof where and how you obtained that cd key don't call them ,because they will request it i assure you.