Section 64. The licensing authorities after notice to the licensee and reasonable opportunity for him to be heard by them, may modify, suspend, revoke or cancel his license upon satisfactory proof that he has violated or permitted a violation of any condition thereof, or any law of the commonwealth. If at any hearing a licensee is charged with serving or selling alcohol or alcoholic beverages to a person under twenty-one years of age, written notice of said allegations shall be sent by the licensing authorities to the parent or guardian of such person. If the license is revoked, the licensee shall be disqualified to receive a license for one year after the expiration of the term of the license so revoked, and if he is the owner of the premises described in such revoked license, no license shall be issued to be exercised on said premises for the residue of the term thereof.

If it appears to the commission that a license has been issued under this chapter by the local licensing authorities in excess of the quota prescribed by section seventeen or in violation of section sixteen A or any other provision of this chapter, the commission shall, after notice to said authorities and to the holder of such license and after reasonable opportunity for them to be heard by it, revoke such license, whereupon such license shall be surrendered to said authorities, and the decision of the commission shall be final and conclusive. The holder of a license so revoked shall not be subject to prosecution for any sales theretofore made by him under such license on the ground that such license was illegally issued. The city or town whose licensing authorities issued any license so revoked shall forthwith refund to the holder thereof the entire fee paid therefor and authority is hereby granted to such city or town to pay the same out of any funds available.