If the organiser of an event requires needs to know who can attend by a certain time, they set a response deadline that will be visible to everyone who has been invited. Members will not be able to press attend or decline after the deadline has passed without sending a message to the host. If a member has not responded by the deadline ,they can still decline the event to clean up their app.
You can set a response deadline on both one-off and recurring events.
Administrators can still change the status of the participants after the response deadline has passed. This process is described in “How do I change others answers”?
Admins can also set an automated reminder to be sent out 48hrs before the response deadline.
NOTE: The response deadline setting is only available for events where default attendance is set to unanswered.