N.H. Rev. Stat. Ann. § 225-A:4-a

Of the first appointments under this section one member shall be appointed for a term of one year, one for a term of 2 years, one for a term of 3 years and one for a term of 4 years, and until their successors are appointed and qualified, and thereafter each of the appointed members shall be appointed for a term of 4 years and until his successor is appointed and qualified. Vacancies in the board shall be filled for the unexpired term.