Monetization?

The front page says "get started for free" and "book a demo for large events". What is "large"? Presumably "large" events cost money? If I create a workflow for a classroom here, is it free? What if it's a "large" class? If it's free, will it probably be free next year?

I realize that someone needs to pay for all of this, but please be up-front with how all of that works. It makes me extremely anxious to devote time and effort into building something with a platform when the details of the bill are vague/nonexistent.