Section 9. If, in the opinion of the licensing authorities, a licensee as an innholder or a common victualler ceases to be engaged in the business he is licensed to pursue, or fails to maintain upon his premises the implements and facilities required by this chapter, they shall immediately revoke his license. If a licensee at any time conducts his licensed business in an improper manner, the licensing authorities, after notice to the licensee and reasonable opportunity for a hearing, may upon satisfactory proof thereof suspend or revoke his license. An innholder who violates section seven shall forfeit his license. A licensee who is convicted a second time of the violation of any of the provisions of sections six to eighteen, inclusive, shall forfeit his license.