Section 40. The board may suspend or revoke any registration made under section thirty-nine, thirty-nine A or thirty-nine B and any permit issued thereunder for any violation of the law pertaining to the drug business or the sale of alcoholic beverages, as defined in section one of chapter one hundred and thirty-eight, or for any violation of the rules and regulations established by the board, or for aiding or abetting in a violation of any such law, rules or regulations; but before such suspension or revocation the board shall give a hearing to the holder of the permit, after due notice to him of the charges against him and of the time and place of the hearing. Such holder may appear at the hearing with witnesses and be heard by counsel. Witnesses shall testify on oath and any member of the board may administer oaths to them. The board may require the attendance of persons and compel the production of books and documents. Three members of the board shall be a quorum for such a hearing, but no registration or permit shall be suspended or revoked unless upon the affirmative vote of three or more members thereof.