how to update for 10 do the new update
how to update my mac book
MacBook Pro 13″, macOS 10.12
How old is your Mac? I see that you're running Sierra now.
Go to apple logo in menu bar and click about this Mac to see how old it is .
After that, follow these steps to see if you can still get updates
Update macOS on Mac – Apple Support (UK)
If this is not working, type your Mac model here, or type it in Google to see if your Mac is still eligible for updates