Just like the title says. I don't want to come to the point where I don't like Windows 10 and can't revert back to Windows 7 because I upgraded. Anyone have a simple, yet certain, yes/no answer?
The answer is no. The Windows 7 key will never become invalid
unless Microsoft in their infinite wisdom starts invalidating old Windows keys. You will (hopefully) always be able to return to Windows 7.
I know this as I have a custom Windows 7 Ultimate ISO with the key embedded for my 5 PCs.
Update: Microsoft legally cannot invalidate the Windows 7 licenses. The terms of the Windows 10 EULA makes no mention of the key used to upgrade to Windows 10 would become invalidate. The Windows 7 and Windows 8.1 EULA makes no mention of it either. Microsoft would be sued by the EU faster then butter melts on toast if they did that.
Thanks to RamHound for that.
Actually it DOES become invalid one month after the upgrade.
If it's an OEM royalty key, (usually the case) they can't invalidate it. if it's a oem system builder or retail product it WILL invalidate after one month and will no longer activate online.
after the fee upgrade, the rollback option will be there for one month. you can use it during that time. when it disappears they will invalidate your windows 7 COA key.
You will still be able to reinstall your Windows 7 (on the same machine)
[Update] [This post]1 on Microsoft’s own support board describes someone who downgraded from 10 to 8.1 with help from Mircosoft tech support.
So, Microsoft obviously sees nothing wrong with downgrading.
And in this post, someone asks
If I install windows 10 on my Desktop, am I able to revert back to Windows 7 if I dont like it?
and the forum moderator, who one can presume speaks for Microsoft, or at least ought to be knowledgeable about these things, says
Yes you can:
Can I uninstall Windows 10 if I do not like it or something goes wrong?
See the following: How to: Rollback to a previous version of Windows from Windows 10