I’ve edited your thread header; it’s good to give people an idea of what a post is going to be about.
By age limit, do you mean when you get so decrepit that you’re kicked off the board? Not that I know of.
In fact, I assume you’re asking if there’s a minimum age, which is how I edited your header. No. I personally don’t see the point, as there’s no way to verify that and birthdate is optional here. We assume literacy. The one thing to be aware of is the MR has a “family-friendly” policy, by which you can roughly assume older child at the earliest. No worries about discussing Santa, for example.
Who is totally real, btw.