Once your puppy reaches the age of 6 months or so, it's likely that your municipality requires that you license him. License laws vary by state and municipality, as do fees and fines for keeping an unlicensed canine. If you're not sure how to license your dog in your community, contact your local animal control agency or municipal or city officials. Your veterinarian also can advise you on local license requirements, as can animal shelters.
You'll probably need to provide proof of a current rabies vaccination to license your dog. Some local ordinances require higher annual license fees for canines who aren't spayed or neutered. Depending on your locality, you might receive a new license with a different number each year, or keep the same tag and license number and renew the license annually. Dog licenses are generally good for a calendar year starting in January and ending on the last day in December.