At the heart of Twelve Step programs are the 'Twelve Steps' and 'Twelve Traditions' which originated over 50 years ago in the Alcoholics Anonymous program. There are now many variations of AA focusing on a wide range of habitual behaviors, with millions of 'anonymous' people participating in hundreds of meetings around the western world. The original Twelve Step programs were heavily organized around Christianity, referring to a higher power as represented by 'God'. However, since AA was the original Twelve Step program it is to that particular addiction I will chiefly refer. In other words, no one wants your money and no one has an investment in you being there.
Some people go to a meeting once a day, some once a week, still others once every few months.
People don't need to register, or sign up, or reveal their name, or where they work, or even say anything if they don't want to. Donations are taken but not required and any money raised is merely to cover the cost of hiring the room and coffee. Anyone wanting to go to a meeting can just walk in and sit down. Going to a meeting is part of 'working the program'. One goes to a meeting and benefits by 'sharing'.