Multiple Simultaneous Meetings

Free Trial and Professional subscribers may create as many web meetings as they like, provided that only one of those meetings is active at any given time.  Enterprise subscribers are not subject to that restriction, and may run up to 10 meetings at the same time.  Universal subscribers can run 100 meetings at once.

To clarify, "active" in this case means that you actually have people in the meeting room doing things.  You can, for example, have several meetings in existence at any given time, provided you leave one before entering another.