Starting on Wednesday January 15, 2020, the day after the last updates are released, users of Windows 7 will be presented with an option to upgrade to Windows 10. The notification will remain on the screen until you interact with it.
The reminder is also intended to reinforce the risks of using an unsupported operating system. Recall the problems that hit Windows XP not so long ago which now is finally almost completely out of use. Many XP users disliked the poor performance of Vista but when Windows 7 was released it was wildly popular.
While the early releases of Windows 10 had some gaming issues, Microsoft has cleaned them all up. Now games are working fine with very few exceptions.
The OEM Windows 7 and 8 keys with a machine will work to activate Windows. Machines with OEM Windows 8.1 have the key in the DMI so they can have Windows 10 installed without a key and it will activate fine.
If you do not have you key there are ways to get it for you. Magic Jellybean can recover the Windows key and save it so you can use it to activate Windows 10. Magic Jellybean can also recover the Microsoft Office key so you can install that over if you need to.