Microsoft has released its newest Windows 10 Insider Preview Build 10565 which brings plenty of fixes and improvements but also brings an important change for the activation process, allowing Windows 7/8/8.1 keys to be used to activate Windows 10.
While it was earlier possible to install those previous versions of Windows OS and then upgrade to Windows 10 OS for free, Microsoft has finally allowed users to skip that step and simply enter the product key during fresh Windows 10 OS installation.
There is a minor catch, as the key that you plan to use for a fresh Windows 10 OS installation must have been used to activate the previously installed version of Windows OS, or unless it is a new key, you will need to install previous version and then upgrade to Windows 10.
Hopefully, the same activation process will be available to all users and not just those that are a part of Microsoft's Windows Insider program.
You can check out more info at Windows Blog via link below.
Source:
Blogs.Windows.com.