Many users have a same confusion about what happens if they upgrade a non-genuine version of Windows to Windows 10. Today according to Terry Myerson 's post, if you are using a non-genuine version of Windows and you want to upgrade to Windows 10 then, there will be a watermark placed on your desktop. Microsoft has not yet shown the non-genuine watermark in Windows 10. However, in other versions of Windows, it appears in the bottom right corner and says "This is not a genuine copy of Windows". If you buy a Windows machine that displays this message, you should return it.
He also added in his post that the Microsoft will be offering “attractive” Windows 10 offers to non-genuine Windows users.
One area Microsoft has not yet clarified is if you are part of the Insider program and upgraded a non-genuine build to the new OS, if you will still see this watermark.
Source: Microsoft via NEOWIN
