Md. Code, Tax - General § 9–323

(a) Except as provided in subsection (b) of this section, a license or an exemption certificate expires on the first May 31 after its effective date.

(b) A Class “G-Temporary” license expires on the earlier of:

(1) termination of the contract for which the license was issued; or

(2) the first May 31 after its effective date.