Free upgrade still working using old keys

A few days after the 29th-July free upgrade date passed, a few people on this forum (myself included) were still reporting that new clean installs of Win10 could still be done using old Win7 keys.
Not talking about re-installs, but new installs with old Win7 keys that had never been used.

Has anyone tried this again recently ? Curious to know if Win10 can still be activated with old Win7 keys,

Cheers

Windows 10 free upgrade offer still works. I tested today. First I installed and activated Windows 8.1 (I used an old Windows 8 key that had never been used) and after this I upgrade to Windows 10.

Windows 10 - Upgrade Installation - Windows 10 Forums

3. Do the step below depending on how you want to upgrade to Windows 10.

•step 4: To Upgrade to Windows 10 using Windows 10 Upgrade Assistant
•step 5: To Upgrade to Windows 10 using Media Creation Tool
•step 6: To Upgrade to Windows 10 with an ISO file
•step 7: To Upgrade to Windows 10 with USB Installation Media

Note that Windows 10 upgrade installation does not accept Windows 7/8.x product key, so you need to select the option I'm reinstalling Windows 10 on this PC (see screenshot below).



You can also clean install Windows 10 and activate it directly with your unused Windows 7/8.x product key.

Windows 10 - Clean Install - Windows 10 Forums

alphanumeric said:

Was Windows 10 ever installed and activated on that PC, prior to your test?

No.

I created a new virtual machine and I installed on a virtual machine (VMware Workstation 12 Player), when I installed Windows 8.1 and upgraded to Windows 10.