When a function inactivation process is instructed on an MFP A, all the functions are inactivated and a function inactivation certification key is issued, and then resources related to the functions are transmitted to an MFP-B. When reception of the resources is completed on the MFP-B, a function duplication completion certification key is issued. When these keys are input to a licensing server, a database is updated, and a function activation key is issued. When the function activation key is input to the MFP B, the functions related to the transmitted resources are carried out.