Sublime 4 is like a different world. There might be hiccups with moving to different versions but you can always ask at the discord server.
I think their license works for the current version at time of purchase and next version, so you’re good to go till version 5
The licensing used to be for a single major version. This was changed with Sublime Text 4: A license is permanently valid for any versions/builds released within 3 years of the purchase. See https://www.sublimetext.com/blog/articles/sublime-text-4