Our tennis meetup group, "Tennis Portland", has been playing since 2007.
Dues are used to pay real costs: we pay to http://www.meetup.com/about corporation. "Annual membership": you can play for one year from the payment date.
We play all year long. Some people incorrectly assume that courts could be wet in the winter. If everything is wet outside, but the organizer signed up for game it means courts are dry even if everything else is wet outside.