The deadline for registration can be set for each category and can also be changed. You can select "Categories" in the left column of the desired event and then move the date in the "Deadline" column of the desired category. 

If ticketing is activated, the registration deadline can also be controlled by the availability of the tickets. To do this, select "Ticket types" in the left column and then click on the green pen button to edit the desired ticket. 

In the window that then appears, you can change the period in which the ticket is available. To finish, always click Save at the bottom right.