Windows 10: Windows 10 Key after upgrading from Windows 8

I have been subscribed to the insider preview and had all the builds of Win 10 as they have been released when Win 10 went RTM I unsubscribed and installed Win 8 Pro and registered using my legit Win 8 Pro key afterwards I upgraded to Win 10 RTM from Microsoft updates and after activation I expected a new Win 10 key - in fact after activation the key is the generic key I was using for the preview builds but Windows is permanently activated, anybody else noticed this?
When I upgraded my other computer which was running licensed copy of Win 8 and had never been used for the insider program I got a new Windows 10 key after upgrading, however when I reinstalled Win 8 on the machine that had previously been used on the insider program and then upgraded to Win 10 I did not receive a new key - its the same key that I have been using whilst running Win 10 Preview!
So why do I get a new key on the machine that never was on the insider program and the machine that was stays with the generic key?

:)

 

Reinstall or clean install of Windows 10 Pro

Start Windows 10 setup by launching it from within Windows 8, click on the Setup.exe. This will ensure that you upgrade Windows 8 to Windows 10.

If you boot from DVD via the Windows 10 DVD you will be given the choice of a Custom install, or an Upgrade install. A Custom install will take you down the Clean Install patch which is no good to you (initially) as you don't have a Windows 10 Product Key.

After performing the Upgrade install from Windows 8 to Windows 10, you can later clean install Windows 10 (on the same machine) without any Product Key in any subsequent installs, but you must have upgraded from Windows 8 first.

Can I clean re-install Windows 10 after upgrading?

Can I clean re-install Windows 10 after upgrading?

 

Clean installed, hard drive wiped, can't activate

If your computer shipped with Windows 8 or 8.1 the product key should be recorded in the UEFI. Install Windows 8.1 without entering any product key. After installation, use this command in an Administrator Command prompt to retrieve the product key from
UEFI and activate with it:

wmic path softwarelicensingservice get OA3xOriginalProductKey

There is no Product Key used to activate Windows 10 free upgrade. It activates by upgrade not by Product Key. The Product Key embedded in the free upgrades is blocked and is not used to activate.

Upgrading from an activated, qualified Windows 7 or 8 OS will result in an activated Windows 10, if the upgrade is done properly and no product key is entered at any time during or after the upgrade. If you use setup.exe from the matching ISO, choose to
Keep Windows settings and files. The ISO must match the edition of Windows 7 or 8 being upgraded (Pro, Home, Single language, etc.).

 

It's not the key that matters. Each motherboard has a unique ID, and Microsoft determines the activation state by checking that ID.
So, once you upgraded from Windows 8/Windows 10 Insider to Windows 10 RTM, the OS will auto-activate itself each time you reinstall Windows 10.

Long story short, no, you won't get a unique key for upgrade.