The Commission, in its discretion, upon application, may authorize the collection of the Use Tax by any retailer or vendor not maintaining a place of business within this state but who makes sales of tangible personal property for use in this state. Such retailer shall be issued, without charge, a permit to collect such tax. When so authorized, it shall be the duty of such retailer to collect use tax upon all tangible personal property sold to his knowledge for use within this State, in the same manner and subject to the same requirements, as a retailer maintaining a place of business within this State. [See: 68 O.S. §1407]