Neb. Rev. Stat. § 60-365

Any person purchasing a motor vehicle or trailer in this state other than from a licensed dealer in motor vehicles or trailers shall not operate or tow such motor vehicle or trailer in this state without registration except as provided in this section. Such purchaser may operate or tow such motor vehicle or trailer without registration for a period not to exceed thirty days. Upon demand of proper authorities, there shall be presented by the person in charge of such motor vehicle or trailer, for examination, a bill of sale showing the date of transfer or the certificate of title to such motor vehicle or trailer with assignment thereof duly executed. When such motor vehicle or trailer is purchased from a nonresident, the person in charge of such motor vehicle or trailer shall present upon demand proper evidence of ownership from the state where such motor vehicle or trailer was purchased.