Hey MajorTom,
Thanks for reaching out to us!
By default, we do have a “Past Events” listing which you can technically go back into indefinitely. You could eventually run into issues, however this would probably happen sooner depending on the type of queries you’re running on the information rather than just the amount of information causing the problem.
We do have a cleanup of recurring events which I believe is set to remove recurrences of an event that are older than 2 years. However you could technically also set those to stay in your database forever as well.
Let me know if this helps.
Thanks!