A processing device comprising: a storage unit adapted to store device-specific information in association with device identification information for identifying each of a plurality of devices; an authentication key request reception unit adapted to receive an authentication key request including the device identification information; an authentication key issuing unit adapted to issue an authentication key in response to the authentication key request, to transmit the issued authentication key as a response, and to store the issued authentication key in the storage unit in association with the device identification information included in the authentication key request; a license key request reception unit adapted to receive a license key request including the device identification information and the authentication key; a license key issuing unit adapted to issue, when the storage unit stores a combination of the device identification information and the authentication key included in the license key request, a license key for receiving a predetermined service related to the device, to transmit the issued license key as a response, and to store the issued license key in the storage unit in association with the device identification information included in the license key request; a user identification information registration unit adapted to store user identification information of a user who has presented the license key, in the storage unit in association with the device identification information associated with the license key; and a device control unit adapted to integrally control the plurality of the devices identified by a plurality of pieces of the device identification information associated with the same user identification information. a storage unit adapted to store device-specific information in association with device identification information for identifying each of a plurality of devices; an authentication key request reception unit adapted to receive an authentication key request including the device identification information; an authentication key issuing unit adapted to issue an authentication key in response to the authentication key request, to transmit the issued authentication key as a response, and to store the issued authentication key in the storage unit in association with the device identification information included in the authentication key request; a license key request reception unit adapted to receive a license key request including the device identification information and the authentication key; a license key issuing unit adapted to issue, when the storage unit stores a combination of the device identification information and the authentication key included in the license key request, a license key for receiving a predetermined service related to the device, to transmit the issued license key as a response, and to store the issued license key in the storage unit in association with the device identification information included in the license key request; a user identification information registration unit adapted to store user identification information of a user who has presented the license key, in the storage unit in association with the device identification information associated with the license key; and a device control unit adapted to integrally control the plurality of the devices identified by a plurality of pieces of the device identification information associated with the same user identification information.