I've
had a read around (scroll to Step 4 Point 2), and it seems the only way to convert a Windows 7/8/8.1 licence key to a Windows 10 licence key is to begin the install process, choose, "Clean Install", and enter your pre-existing key. This should then register your pre-existing licence key with the Win10 servers and allow you to use it for a Win10 Clean Install whenever you like.
Question is: is it possible to have your key so registered and yet then cancel the Win10 install and stay with your current OS? Obviously the point would be to stick with your current OS and yet have a valid Win10 licence key for clean install-purposes after July 30th.
Any tried this?