The majority of the US has little or no direct regulation over the practice of Hypnosis or Hypnotherapy.
Laws for operating a business still apply, for example Truth in Advertising, Insurance requirements, Unfair business practices, etc.
There is currently no agreement across the profession as to what hypnosis is, how it works, or necessary training or education to become a competent hypnotist. This is both good and bad news.
The good news is that hypnotists are free to learn hypnosis as they choose, then open a practice with minimal regulation and requirements. The only states that have specific requirements are : Colorado, Connecticut, and Washington State.
The bad news is that because there is little oversight, it's possible to open a hynosis practice without sufficient professional training. This is often the case with weekend courses, or online training. While both can produce competent hypnotists (primarily because anything is possible), it is unlikely to produce competent, professional hypnotists that will open thriving practices.