As a computer tech I still find it a need to upgrade a Windows 7 device to Windows 10 and it is still possible to do so free, using the Windows 10 Media Creation Tool
https://www.microsoft.com/en-us/software-download/windows10
So I downloaded it to my Windows 7 laptop and started the upgrade choosing the clean install option. After it was done I checked the activation and it was good to go, activated.
So why? Could Microsoft have simply overlooked the activation server and failed to reset it? Doubtful!
It is more likely that Microsoft just turned off the nag popups and stopped making announcements that it was still free. The most likely reason is Microsoft is still allowing free upgrades is to get more copies of Windows 10 on Windows 7 systems. After all Microsoft intends to set up Windows 10 as a monthly fee system.
So if you feel brave enough to step out of Windows 7 and go to Windows 10 download the Media Creation Tool and let it do its thing.