It depends upon age and which level Medical Certification required by the Operator or Federal Air Regulations.
ATPL requires Class 1, Commercial requires Class II, the Operator may require a Class 1 by Company Policy.
Bell 407 VFR only Operations generally only require a Commercial License with a Class 2 Medical.
US FAR Part 61 sets forth the requirements for level of flying license
US FAA terminology uses "Certificate" rather than "License".
This link explains the standards for the medical.
https://www.faa.gov/about/office_org...ide/standards/