A removable non-volatile memory device durably stores a serial number or identifier, which is used to mark multimedia content legally stored on the removable non-volatile memory device. In order to retrieve the serial number, a host electronic system coupled to the removable non-volatile memory device sends a sequence of multiple file access commands to access a predefined target file stored on the removable non-volatile memory device. In accordance with the executed predefined sequence of multiple file access commands, a corresponding sequence of data access commands are received at the removable non-volatile memory device and are interpreted as a request by the host electronic device to read the serial number. The removable non-volatile memory device outputs the serial number in response to the sequence of data access commands.