Windows 10: Windows Activation does not recognize my Product Key

I've read all the similar problems I could find but they refer to options that don't seem to exist any more.The old PC is being dismantled and a new machine motherboard, CPU, M2 drive, memory, case is being set up. We previously bought a permanent Windows 10/11 Home license for the old PC as it was a build also not an OEM. We connected the new drive and booted the new PC with it and ran ShowKeyPlus and retrieved the product key. We have the product key license email printed but cannot locate it.We built the new PC, installed Windows 10 and when we try to use the product key an error is sho

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Product key not recognized

I want to thank everyone for taking the time to respond to my query. I have to say some of the suggestions assume a tech capability beyond me.

I think I will find the original receipt, go back to the shop, and ask them for the Product Key, then try again. I suspect it was an unauthorized copy. Maybe that will work.

 

Product key not recognized


According to my computer, Windows7 is activated and is a genuine product. But when I attempt to download W10, it does not recognize the 25 digit Product Key. I don't know what to do.

 

Windows 10 product keys and activation - and the KMS angle

Changing the product key to the generic Windows 10 product key will reset activation to the standard retail channel for activation. It might just activate (if there was a previous digital license for Windows 10 for that computer established with Microsoft). Once Windows 10 is back on the retail activation channel, then more than likely changing the product key to the Windows 8 product key using the same method may work.