The Tax Commission may in its discretion, upon application, authorize the collection of the tax herein levied 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 and by the out-of-state place of business of any retailer or vendor maintaining places of business both within and without Oklahoma and making sales of tangible personal property at such out-of-state place of business for use in this state. Such retailer or vendor shall be issued, without charge, a permit to collect such taxes, in such manner and subject to such regulations and agreements as the Tax Commission shall prescribe. When so authorized, it shall be the duty of such retailer or vendor to collect the tax upon all tangible personal property sold to his knowledge for use within this state. Such authority and permit may be canceled when at any time the Tax Commission considers that such tax can more effectively be collected from the person using such property in this state. Provided, however, that in all instances where such sales are made or completed by delivery to the purchaser within this state by the retailer or vendor in such retailer's or vendor's vehicle, whether owned or leased (not by common carrier), such sales or transactions shall continue to be subject to applicable state and any local sales tax at the point of delivery and the tax shall be collected and reported under taxpayer's sales tax permit number accordingly.