Can I limit the number of individuals that register for an event through JotForm?

Yes, it's possible to limit your individuals. Please see http://www.jotform.com/help/64-How-to-Set-Unique-Submissions-on-a-Form for more information.

Alternatively, you could also base it of a field, see this http://www.jotform.com/help/223-How-to-set-Form-Limits-Based-on-a-Unique-Question which you might find useful too.