This is a two step process!

Step 1

You have to RSVP, which you probably already did.
Check the list to the right (or below if you are on a mobile device).
If you are on there, then that is SATISFACTORY!

Step 2

You need to pay the Rub!

If you need to pay at the door... 
Do so immediately upon arrival!
Do not make us come look for you.