N.H. Rev. Stat. Ann. § 529:24

The officer shall make a full return of his proceedings, and cause the execution and return to be recorded at length in the registry of deeds of the county in which the real estate lies, and to be returned to the office of the clerk of the court to which it is returnable; and no sale of a greater interest than a term of seven years shall be valid, except against the debtor and his heirs, unless the execution and the return are so recorded.