Section 7. (a) Before declining to grant a license of any type, or suspending or revoking a license, the commissioner shall hold a hearing and grant the applicant or licensee an opportunity to be heard in person or by attorney. A duly attested copy of the order of the commissioner upon such hearing shall be served upon the applicant or the licensee in the manner provided by section nineteen.

(b) Any licensee whose license has been revoked or cancelled shall upon notice thereof forthwith deliver and return said license to the commissioner or to any authorized representative of the commissioner.