Software for operating a digital camera is installed in a personal computer. The software takes out a serial number of the digital camera, which is connected to the personal computer, when firstly booted. The serial number is sent to a server via the internet. The server checks the received serial number against ledger data. When the received serial number is not registered, this serial number is recorded in the ledger data. The server charges a dealer a royalty of the software in accordance with a user number counted every predetermined period. The dealer requests a monetary facility to transfer the royalty of the software to an account of a right holder of the software.