I have just purchased a Windows 10 pro key from ebay, and it doesn't work.
The seller states that the key will only work on a clean install of windows 10, and not as an upgrade.
I have used the windows media creation tool (https://www.microsoft.com/en-us/software-download/windows10) to create a bootable usb.
However it always install windows home edition, could this be the issue.
Regards