Event loyalty / membership schemes

Hi Tribe
To create a bit more exclusivity and community as well as create additional revenue for my event i’m considering setting up a loyalty scheme programme,where attendees get a loyalty card we stamp 3 visits ,with the 4th visit being FREE.

I wanted to trial this and then progress onto a one off payment for MEMBERSHIP that gives you access to:
-Priority tickets
-Discounts off merch

Are there any thoughts or suggestions you may have in setting up something like this?

ONE of my main concerns is- how will the attendee register that they have had 3 visits when securing a 4th free ???

kind regards