on paid 3, i get a popup every time i try to do anything telling me i must upgrade and pay again, so i've steadily just stopped using sublime. Didn't install it on the new computer

I don't like that it upgrades to ST4 without telling you, but there's a simple workaround if you want to continue using your ST3 license. Download the latest stable build of ST3 from their website:

https://www.sublimetext.com/3

And then add

  “update_check”: false