I have a Win8.1 Enterprise key. It was acquired via volume licencing.
I have a new PC that came with Win8.1 (OEM).
Is there any way to upgrade to Win8.1 Ent from Win8.1 (OEM) without a clean install?
EDIT: I attempted using "Add Features to Windows 8.1" and get the following error:
This key won't work. Check it and try again, or try a different key.
Short answer:
No there isn't. Microsoft does not support an upgrade path between OEM/Retail editions of Windows and Volume License editions. That's just the way they made it unfortunately. If you tried to hack it somehow, you'd be fighting their anti-piracy mechanism, whose whole job in life is to prevent pirates from doing exactly that sort of thing.
Long answer:
Even though the only difference between Win8.1 Enterprise and Win8.1 Pro is the way they're licensed, the .dlls and associated registry keys that control product activation are different between the two. The Enterprise version only supports KMS/MAK product keys, but the Pro version only supports OEM/Retail keys. Additionally, the Enterprise version allows online activation via your own corporate activation servers rather than Microsoft's, but the Pro version does not support that. On the flip-side, the Enterprise version does not support OEM certificates in the firmware the way the Pro version does. They also differ in the way they handle hardware changes and the activation grace period.
As you can see, the Enterprise version's licensing service offers certain features but lacks others and vice-versa for the Pro version. These differences are hard-coded into the activation .dlls themselves and are not based on a config file or reg settings. And because Microsoft's anti-piracy mechanism is buried so deep within the operating system, you can't just change them out without breaking the OS.
