N.J. Stat. § 45:14C-18
Every State license issued hereunder shall automatically expire on June 30 following the date of its issuance. Licenses may be renewed annually by the State board upon written application of the holder and payment of the prescribed fee and renewal of required bond. Such license may be renewed without the holder having to be re-examined, provided said application for renewal is made within 30 days next preceding or following the scheduled expiration date. Any applicant for renewal making application at any time subsequent to the 30 days next following the scheduled expiration date may be required by the State board to be re-examined, and such person shall not continue to act as a State licensed master plumber, as described in this act, and no firm, corporation or other legal entity for which such person is the bona fide representative shall operate thereafter under a State license in the plumbing business, as described in this act, until a valid State license has been secured or is held by a bona fide representative.
Any State license expiring while the holder thereof is outside the continental limits of the United States in connection with any project undertaken by the Government of the United States shall be renewed without such holder being required to be re-examined, upon payment of the prescribed fee at any time within 4 months after such person's return to the United States.
N.J.S. § 45:14C-18