Operating system
If I can't upgrade past 10.13, do I need to get a newer computer?
Earlier Mac models
That depends. do you need to run software or do anything that requires a newer version of macOS?
If you use email, and light web browsing, it probably not entirely necessary to update at this time, but it would be a good time to start thinking about it. Maybe start saving some money to get a newer computer in say 2 to 3 years.
