I've just noticed that the upgrade notification window mentions that I need to upgrade the license... so I checked out the news on their website and it seems they've switched from licenses being valid for a major version, to only being valid for 3 years. This feels like a bit of a rug pull on an already very expensive editor. I won't be renewing and I guess this is the end of the line for Sublime and I.

FWIW I checked the website after reading your comment and I found out that the license terms changes were announced in 2021 with the introduction of Sublime Text 4 (https://www.sublimetext.com/blog/articles/sublime-text-4).

I also didn't notice that, it feels like an implicit subscription. However, I should point out that the developers of Sublime Text have always been quite generous in letting people use the app without paying, while only showing a nag window every once in a while.