I apologize if this has been covered in a thousand different topics already, but this has proven surprisingly difficult to find information on. Even in this forum, I'm not really sure what search terms to use to find what I'm looking for. Reinstalling is not an issue for me, but my friend is not so tech-savvy. I wanted to use one of my (legit) Enterprise keys on their computer so I could enable some QoL features for them. What I discovered is that OEM versions of Windows can't be upgraded by normal means, even with the diagnostic keys. They try to force you to purchase the Professional upgrade in the Windows Store for $100. Is there a way to get a Retail key working on this OEM installation, while disrupting as few things as possible?