N.D. Cent. Code § 4.1-33-08
A certificate issued under section 4.1-33-07 expires as of the first day of April following two years from the date of issuance. A certificate is renewable every three years on April first. A certificate may be renewed upon completion of a seminar approved by the board or upon successfully completing an examination required by the board, or both, if required by the board. The board shall require a person holding a current valid certificate to take an examination within the three-year period if the board determines additional knowledge related to classifications for which the applicant has applied makes a new examination necessary or that a new evaluation is necessary to assure a continuing level of competence and ability to safely and properly use pesticides.
N.D.C.C. § 4.1-33-08