I looked at the page, but didn't read the definition of "perpetual fallback license". Thank you for the clarification.

It still seems bizarre that one standard case is that you pay for a subscription, presumably using version x, and then are pushed down to version x-1 if you didn't subscribe for at least a year under version x.

Thinking about it a bit more yeah, when you stop subscribing you might have to roll back 12 months of updates on your machine, which is pretty odd. Clearly they want to discourage you from doing it.

At least bug fixes are included:

"The license also includes all bugfix updates, more specifically in X.Y.Z version all Z releases are included."

I can understand giving you the major version at the time you bought the subscription but it's a bit stingy to exclude minor version bumps (Y releases).

It's not minor version bump. JetBrains doesn't use semver. X.Y is typically a major release, with X being the year (e.g. 2017.2)

That's an unrealistically forgiving outlook on this.

You're forced to upgrade when the language you're using upgrades. Or the ecosystem around the product evolves. The IDE doesn't live in a vacuum that will work in perpetuity.

It's realistically much closer to renting than buying as once the updates stop it's not that much longer until the product is no longer usable in a modern environment. Simple example would be if you want to use Kotlin 1.1.4 (latest stable) you must be using Intellij 2016.2 or newer to get the corresponding 1.1.4 kotlin plugin. And if you use an older plugin, the IDE will complain at you and things will be buggy and not work right. Similarly since gradle support is built into the IDE at some point that will fail if your IDE is no longer being updated.

It's not realistic to avoid updating the IDE for long. That's why Jetbrains prominently features subscription and yearly renewals - because you're very nearly forced into it.

You can hardly blame them for this situation though. They obviously have to do work to keep the IDE up to date.