Our club is an Academy of Model Aeronautics (AMA) club and membership in the AMA is required. The AMA site can be reached here.
Starting in 2016, the Federal Aviation Administration (FAA) required user registration and model markings and having an FAA ID was a requirement to fly at our club field. The FAA site can be reached here.
Update, 12/12/2017: Trump signed the bill requiring the FAA to register; if previously registered, and you did not request removal from the database, you’re still registered; no action required.
Update, 7/9/2017: With congress reauthorizing the community based organization (AMA) responsibility for model operations, the FAA is enabling previously registered folks to either have their previously submitted information to be purged from the FAA database and/or to have the $5 registration fee refunded. The forms can be obtained here.