We run into no-shows all the time. Most members say they do not know how to cancel on the app. Burying the cancelation option behind the barely noticeable 3-dot menu in the top right corner of the app is not intuitive for most members. My suggestion is to add a Cancel button right next to the Check-In button. This would of course only be available on events that the user has booked. You would still need to verify that you actually want to cancel.