There was some confusion, and I'm not sure if they changed policy, but IntelliJ gave you a perpetual license for the version on the day you purchased it, not the last version at the end of the support contract
> When purchasing an annual subscription, you will immediately get a perpetual fallback license for the exact version available at the time.
https://sales.jetbrains.com/hc/en-gb/articles/207240845-What...
(That is, the next sentence in the bit you quoted is:)
> You will receive perpetual fallback licenses for every version you’ve paid 12 consecutive months for.