Windows 10: Win10 Pro Product Key on old machine needed for new one

and of course I have no idea where my record of my product key for Win10 Pro retail got hidden.

I've tried the CMD and Powershell methods and no go.

How do I get my product key so I can use it my new machine?

I am posting from the old one that has the key right now.

:)

 

Cannot upgrade to Windows 10 - Unique Product Key situation

No... let me try again.

• Old computer is running Win7 Pro (SP1) with a Product key I have from a few years ago. The Product is activated already, but I do NOT use this computer at this point, so I didn't worry about using the Product key when moving to the new computer (see below).
  
• New computer is running Win10 Pro, with data and OS migrated from the Old computer, (same Product key as above), then Upgraded to Win10 (without getting a new Product Key).

What I am trying to do now...

• I want to upgrade the OLD computer (Win7 Pro) to Windows 10... using a new Product Key I just purchased.
• I have tried to do this internally, and also using the ISO burned to a thumb drive. But it does not want to work.
• Steps:
  • Start from USB drive.
  • Enter New Product Key (or click "I don't have one").
  • Install initiates and then tells me to restart from Windows and then open the installer again to continue.
    • At this point, I actually need to Quit the installation to restart the machine.
  • When restarted, I go to the USB drive and restart/resume the installation process.
  • I have tried to download and not to download updates, but when the installation fails, I see the message, "Something happened" and "Setup has failed to validate the product key".
  • NOTE This happens if I enter the NEW Windows 10 Product Key, or if I skip that step (which I assume means that it will use the old Windows 7 Key for the upgrade).

 

Reusing upgrade key to Win10 Pro on a new machine

I upgraded my computer to Windows 10 Pro (from Home) and then shortly after that it stopped working due to a corrupted drive. It was unrecoverable and I wasn't able to uninstall/deactivate Windows on this device. I bought a new device with a fresh version
of Windows 10 Home, and I wanted to use the same key to upgrade, but when I attempted the upgrade on the new machine it told me the key was invalid. I assume this was because the old machine is still "using" the key. Is there a way to decommission non-usable
machines or remotely deactivate product keys via a support request or some other means?

 

Swap product keys between machines

I have a now deceased PC with Windows 10 Pro and a new laptop with Windows 10 Home. In the process of moving all my files to the new machine, the power supply of the old machine blew up. I'd like to swap the product keys and eventually resurrect the old
one. Is this easily done (the swapping I mean)?