The first part of my question was where can I get my Windows 8 Key but that has already been answered elsewhere.

The second part is if I do the free upgrade to Windows 10 from Windows 8.1, can I use the old Windows 8 Licence in a VM Guest or on another PC? Or is that against Microsoft's licencing laws?

Thanks in advance

  • The W8 key is absorbed into the w10 upgrade, so no, but you can go back to W8 on the original pc if you decide later.
    – Moab
    Dec 22, 2015 at 15:45

2 Answers 2


I'm suspicious it would not activate correctly, as the Windows 8 key is likely in your UEFI and tied to the hardware. The virtual machine will report different hardware.

This should answer your question regarding licencing


Q. Can I install OEM software on a virtual machine (VMware)?

A. You can install OEM software in a virtual environment as long as you have a separate license for each instance of the software. It is fine to use the OEM version as long as it is properly licensed. To be clear, a separate version of the software must be installed for both the “standard” and “virtual” installations.

As your licence is now 'activated' for Windows 10, it would be against the licence.

  • Interested why this attracted a down vote?
    – Jonno
    Dec 22, 2015 at 13:15

No. It won't activate. You can use it to install Win8.1, but you'll need to activate online, and that's where it'll be rejected. The key is marked at MS as "used".

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