Earlier quoted context omitted.
Isnt it just a simple subscription model with a 3 year term?
I think this implies that after 3 year, you can keep using whatever is the last version you were using. It's basically license to get what you have right + any versions in the next 3 year. JetBrains also has a similar license for yearly subscriptions, where you can keep using whatever version was supported at the end of the license.
You get a license and access to all updates released for duration. But if your license is not renewed at the end, you lose access to updates in the year/time since you bought the license.
You still keep original version at the time you purchased license for as long as you want, though.