Windows 8.1 pro

[Reko420]

I have a unused key for Windows 8.1 pro can I do a Clean install with that to get pro on my new surface 3?

 

[GreyFox7]

I have a unused key for Windows 8.1 pro can I do a Clean install with that to get pro on my new surface 3?

You don't need to do a clean install you can upgrade by running the Windows anytime upgrade tool and entering the Pro Key.

see article ...
https://www.petri.com/change-windows-8-1-edition-without-reinstalling