You could call Windows 8 from 7 an upgrade; there is no 9 and you may as well got all the way to 10 which will soon become just Windows and remain there.
You will have to buy a copy of Windows 10 because you've missed the opportunity to upgrade free of charge.
You could buy an extra hard disk and download Windows 10 from the Microsoft website then install on to that disk. You have thirty days before the activation period runs out, to decide whether to keep it and buy a product key or stick with 7.
Windows 7 will be dropped from updates in 2020 but they did that to XP years ago and it still works perfectly well and not being updated every other week is quite peaceful.