Sometimes your members might bring in guests and you decide you want to check these guests in too. Perhaps you wish to charge the member for additional day passes or just to correctly track attendance.
While the check-in button disappears after a member has checked in, you can check that member in multiple times on the same day time in the check-in calendar. To get there, go to the member's page and click on "Past Check-Ins" in the Check-Ins panel.
You can then check in the member multiple times by clicking the +Add symbol on the day of your choice.