User24 Flarum used to use the bundled Pusher extension on discuss.flarum.org. Now we use the self-hosted paid websockets extension.
I don't remember if we switched because of the Pusher free plan limits or for other reasons.
I'm using the Pusher free plan on multiple of my own projects and have never been close to reaching the limits yet.
It's also worth noting that you can easily switch extensions later, since they don't store any special data that would need to be migrated to another extension. They are fully interchangeable at any time. So there's no downside to start with Pusher free plan.
