Windows 10 Upgrade - product key on 2 machines?

I recently had a local computer shop build me a new PC. They used my old PC's Windows 7 product key, as I won't really use that any more (started suffering from occasional BSOD and I figured it was due an upgrade anyway so didn't look into reasons)
They said the old key will work fine on the new PC and Windows updates will simply stop arriving on the old.

I've been using my new PC since mid-July and It's definitely getting updates. However Windows 10 doesn't seem to be 'ready' for it.

I turned on my old PC yesterday, connected to my network so I could dig out some old files, and it's already started downloading Windows 10.

This confused me! Is Microsoft allowing both PCs to get updates?

I cancelled its upgrade, as it's more important I let my new PC get it first. Then found the MS Media Creation Tool to try and get my new PC to force the W10 upgrade. That's downloading now.

In the mean-time I thought I'd just check I had a valid install of Windows, but it says it can't determine that t the moment!?

I guess I'll let the W10 installer run its course, hopefully it will determine that this is a valid copy. Perhaps then Microsoft may get the message that this is the PC I'd like the product key used for.


Anyone had experience of reusing product keys? And having both machine receive updates?

Could it be they are both now seen as valid installs?

Perfect, thanks I was looking for something to do that. But as you say, I may as well see if it works anyway
If it fails then I'll deactivate the key from the old.

Many Thanks

Well that was weird. Microsoft Windows Media Creation Tool Just got to the end of its installation and closed. Leaving nothing different?!?

Barman - what will happen on the old PC when t's back to being 'trial mode' without a current license. Will it be useable but without updates, or will it constantly ask me to register it?

Hmm, I'm trying to think when I bought the product key several years ago. I think it was an OEM key, so probably didn't like being moved to this new machine. though updates are happening OK. Perhaps my PC shop bodged something to get it working?

This is probably why windows 10 isn't arriving.

Media Creation Tool did say would you like to upgrade now, or create a disk for another PC and I chose upgrade now. I guess I'll try again with making the disk. if it fails again then I know I need to buy a new product key

Well I created the install disc and now I'm tying this from inside my Windows 10 install! My old PC, despite automatically downloading W10, has been sitting on the 'Preparing for upgrade' dialog for about 30 mins, so I guess it's no longer using the product key.

I have to say the upgrade procedure is amazingly smooth, and presented in a very friendly way, Microsoft did this well IMH.

Thanks loads for the replies everyone. My main PC is now on W10, and my unused one still works, though possibly without future upgrades, which is fine by me.

Here's another update - Using the 'Media Creation Tool' for the update my PC upgraded to Windows 10 just fine!
Then I tried upgrading my old PC again (The product key should technically not work on this one) and it failed again, but one last time using the disc and it worked!

So somehow my OEM product key is working on two machines together!