Ask for the name used on the licence
Get the name in full, the number on the licence and the state that issued it. Keep those details together so you can match them to a public record.
If the person has a different role from a doctor, ask which state board licenses that role. Do not assume a doctor search covers everyone.
Use the state record
State medical boards issue doctor licences and publish their status, along with disciplinary history: any action by the board against that doctor.
For individual board websites, the Federation of State Medical Boards supplies a directory.
Use the board directory on the reading page to reach your state board. Open its licence search and match the name and licence details.
Read the whole result
Check the licence status and open any linked action or restriction. Take any unclear entry to the board and request an explanation.
Some states divide doctors' licence records between separate boards.
Keep the result in its proper place
A record with no public board action does not judge how good the clinician is.
It also does not establish that a proposed drug works. Ask about the evidence as a separate part of the visit.