A system comprising a printer and an external device, the printer comprising: a communication circuit that communicates with the external device; a printing instruction receiver that receives a printing instruction; a controller that determines a printing amount based on a state of the communication with the external device; a printing unit that executes printing based on the printing instruction and the printing amount; a storage that stores first printing information; wherein the communication circuit receives second printing information from the external device, wherein the controller determines the printing amount based the first printing information or the second printing information, wherein, during a time until the communication circuit receives the second printing information: the controller determines the printing amount based on the first printing information, the first printing information including a first predetermined value representing a number of printable sheets, the printing unit, when the controller determines that a value of the first predetermined value is no less than a predetermined value, performs printing based on the determination, and the controller updates the first predetermined value based on a number of times of the printing, wherein the second printing information includes printability information, wherein the printing unit: executes the printing in a situation where the printability information includes printable-status information; and does not execute the printing in a situation where the printability information includes non-printable-status information, wherein the communication circuit acquires the printability information, which includes a second predetermined value, from the external device, the system being characterized in that, the greater a number of times the printer fails to communicate with the external device or an amount of time where the communication is failing, the greater a value to which the second predetermined value is set by the external device, and wherein the controller updates the updated first predetermined value to the second predetermined value. a communication circuit that communicates with the external device; a printing instruction receiver that receives a printing instruction; a controller that determines a printing amount based on a state of the communication with the external device; a printing unit that executes printing based on the printing instruction and the printing amount; a storage that stores first printing information; the controller determines the printing amount based on the first printing information, the first printing information including a first predetermined value representing a number of printable sheets, the printing unit, when the controller determines that a value of the first predetermined value is no less than a predetermined value, performs printing based on the determination, and the controller updates the first predetermined value based on a number of times of the printing, executes the printing in a situation where the printability information includes printable-status information; and does not execute the printing in a situation where the printability information includes non-printable-status information,