Windows 7 was so good I'm sure programmers were fired for straying from Planned Obsolescence. Though live support is gone you should be able to download security patches for years to come so pick Defender, AVG, Avast (all good and FREE) or one of the other suggested anti-virus/anti-malware applications mentioned here. Don't forget a firewall. ZoneAlarm is still badass and now has its own anti-virus suite.
Be wary of the big dogs Norton and McAfee. I've found Norton behaving like a virus itself - burrowing deeply into the registry and invading the system making it hell to completely remove. McAfee's installation wanted to know everything about the user which is just too suspicious for me. They may have improved since I dealt with them.
Got another computer on Linux which is a new experience. Mint 19 is the way to go for similarity to Windows and ease of installation. The speed is astonishing, it has a slew of programs as good or better than Windows counterparts and no one seems to write viruses or malware that can penetrate it. It's taking some getting used to after decades as a WinBot. Good luck to you!
