The way I understand it, if you upgraded from win 7 to 10, you can still use the win 7 licence on that PC. And the win 10 licence always works on that PC as you have a digital entitlement to it, as part of upgrade process. People upgraded PC to win 10 to get the digital entitlement and then reinstalled win 7 again.
(I don't know if this is actually true as I have never done it myself)
You just can't run them both at the same time.
So if you went the long way, you could use licence to install win 7, upgrade all its patches and drivers, and then run the win 10 upgrade. And then not use drivereasy again.