Content data distribution system, on-board device, server, communication terminal, and license issuing method

An on-board device (100) transmits to a server (300) first license request information for content for which purchase is being attempted, and receives from the server (300) content data to which is attached a first license issued by the server (300) on the basis of the first license request information. The server (300) transmits to the on-board device (100) the content data to which is attached the first license on the basis of the first license request information, transmits to a communication terminal (200) second license request reminder information on the basis of end-of-operation notification information, and issues a second license for content data on the basis of the second license request information. The communication terminal (200) transmits to the server (300) the end-of-operation notification information on the basis of determination that the operation of the vehicle on which the on-board device (100) is mounted has ended, and transmits to the server (300) the second license request information according to the second license request reminder information.