Hi Barbara,
Can you clarify your question please?
When your registration deadline is hit, your event will close for registration, and no one will be able to get through (whether they're paying or not).
The only way that someone can be registered for an event that is closed is through the back end, if a planner registers the invitee. The planner can also select "No Payments," which allows them to register the invitee without paying at that moment.
Best,
Julia