N.H. Rev. Stat. Ann. § 294-A:23

If a professional corporation ceases to render professional services, it shall, within a reasonable period of time, either dissolve and liquidate or amend its articles of incorporation to delete from its stated purposes the rendering of professional services and to conform to the requirements of the law of this state applicable to business corporations regarding its corporate name. The corporation may then continue in existence as a corporation under the business corporation law and shall no longer be subject to the provisions of this chapter.