N.H. Rev. Stat. Ann. § 105:9-a

The chief of police in any city or town may, in order to meet the requirements set forth in RSA 105:9, employ certified police officers of any other town in this state to preserve order among the persons attending any public meeting or function. Such officers shall have the powers there which they have in the towns for which they are appointed, and their services shall be paid for by the sponsor of the public meeting or function.