Each state can make its own choice about whether to license (or certify) polygraph examiners. Some states have no rules whatsoever, while other states are very strict about internships, procedures, complaints, etc.
Texas used to be strict. But it did away with its licensing via law changes in 2021.
I was the last Texas in-state polygraph examiner licensee. That means that I had to go through the rigorous process of training, internship, reporting, etc. Make sure that your polygraph examiner was licensed in Texas (or your state if applicable) before the rules changed, and/or holds an active license in other states. Both scenarios apply successfully to me, thus I can lawfully conduct a polygraph exam in well over half the states.
I’m currently licensed in Louisiana, North Dakota, and Tennessee. As such I also have direct polygraph capabilities in 3 home states, reciprocal in 4 other states, and can conduct polygraphs in all 24 other states not requiring a license.