I know the official answer from Microsoft is that you cannot downgrade after the one month period, as the system automatically deletes the old Windows files, but has anyone tried downgrading via restoring an old image or using their factory restore discs back to 7 or 8.1? Did the activation on the old copy still worked? I'm only sure for Windows 7 if it's an OEM SLP activation it will work since it doesn't involve Microsoft servers, but what about retail keys and Windows 8? Will Microsoft refuse the activation of the old version? Reason I'm asking is that I've upgraded my tablet (Asus VivoTab Note 8) to Windows 10, it had problems with the digitizer pen, so I had to downgrade back to 8.1, and that downgrade was not pretty, everything was corrupted. Was told the latest preview build fixes the pen problem, so this time round I cloned my 8.1 installation, and in case something happens I'll dump that back in. Only thing I'm not sure about is the activation if the one month expired. Answers are really mixed on this one, some say it will not activate.
I'm not talking about the 10, I'm talking about the 8.1 and 7. There have been talks about after the one month period, your original 8.1 and 7 key would be "consumed" and no longer activate.
I did upgrade from 7 to 10 month later wanted to downgrade and win 7 didn't work no more, called Microsoft and they simply were playing with me for hours in the end I gave up and used Daz loader
Win10 Pro Retail to Win 8.1 Pro Retail remained activated. I looked in the Win8.1 store and the activated machine was still there, so not surprised really.