Md. Code, Public Safety § 5–309

(a) Except as provided in subsection (d) of this section, a permit expires on the last day of the holder’s birth month following 2 years after the date the permit is issued.

(b) Subject to subsection (c) of this section, a permit may be renewed for successive periods of 3 years each if, at the time of an application for renewal, the applicant possesses the qualifications for the issuance of a permit and pays the renewal fee stated in this subtitle.

(c) A person who applies for a renewal of a permit is not required to be fingerprinted unless the Secretary requires a set of the person’s fingerprints to resolve a question of the person’s identity.

(d) The Secretary may establish an alternative expiration date for a permit to coincide with the expiration of a license, certification, or commission for:

(1) a private detective under Title 13 of the Business Occupations and Professions Article;

(2) a security guard under Title 19 of the Business Occupations and Professions Article; or

(3) a special police officer under § 3–306 of this article.