An image forming apparatus includes a CPU, and when a user selects to set (activate) an optional function, the image forming apparatus determines whether a connection to a network is possible. If the connection to the network is impossible, information (data for output) for acquiring a license key for activating the optional function from a management server is output by any method of QR code, NFC or displaying URL. The user uses a user terminal to connect to the management server on the basis of the data for output, and acquires license key data from the management server. When the user enters the license key, an optional function selected by the user is activated accordingly.