I had a meetup group that never really got off the ground, but I had one person in my group that I was getting something like $10 a month from (can't remember the exact amount). I felt so bad I deleted the group because I didn't know if they knew they were getting charged. Tried to message the person a few times. I feel like this is probably a common thing with Meetup where there are groups with people in them that have forgotten, and they don't realize they are getting charged a small amount every month.