Section 167. No person shall represent or purport to represent any prisoner then confined in, or at liberty after having been confined in, any of the penal institutions of this commonwealth or then under sentence to serve a term of imprisonment in any of said institutions, in the attempt to procure or for the procurement of any pardon, parole, commutation of or respite from sentence, unless such person shall first have filed in the office of the state secretary a written statement signed by him and made under the penalties of perjury, stating in substance that none of the provisions of section one hundred and sixty-six has been violated, that such person is acting with the written consent of the prisoner, and that such person has not received or been promised, and does not expect to receive or to be promised, any money or other reward for so acting, except fees or other reward for legal services, the amount of which fees or other reward and a detailed description of which services shall be set forth in such statement. If any person receives any additional fee or other reward for legal services different from that disclosed in the statement referred to in this section, such person shall forthwith file in the same form and manner as the original statement an additional statement setting forth the amount of such additional fees or the exact nature and extent of such reward, with a detailed description of the legal services rendered for such fee or reward. Said statements shall be kept as permanent records in the office of the state secretary and shall be open to public inspection at any reasonable time.