Section 49. The street commissioners and the police commissioner of Boston, the aldermen of any other city, or the selectmen of any town may, if in their opinion public convenience so requires, license any reputable person, upon the payment of an annual license fee, established in a town by town meeting action or in a city by city council action, and in a town with no town meeting by town council action, by adoption of appropriate by-laws and ordinances to set such fees, to maintain a vehicle for the sale of food in such part of any public way and during such hours as they may designate; provided that public travel is not incommoded thereby, but in no event shall any such fee be greater than one hundred dollars. Any such license may be revoked by them at any time.