To practice the art of massage therapy, the amount of knowledge you must have is determined by the state in which you practice. Some states require full licensure, while others need a certification. There are even some states, where you need either.
In North Carolina a license is required. If you are learning in-state, you must complete 500 hours of in class hours of supervised instruction at a state approved school.
You must also complete a certain number of continuing ed classes per year to maintain your license.
Massage therapy as a healing process is getting stronger every year, make sure that your therapist is licensed.