Section 4. Such license shall state the name and address of the licensee. Such license shall be conspicuously posted in the specified office of the licensee and shall not be transferable, except as hereinafter provided, or assignable. Before any licensee changes such office from one location to another he shall give written notice thereof to the commissioner who, if he approves said change, shall issue without charge an endorsement indicating the change and the date thereof, which endorsement shall be attached to the license for such office and shall constitute the authority for the operation of the business under such license at such new location.