A cartridge containing a dose of at least one substance for preparing a liquid product, e. The latter includes an optics array for receiving measurement light and a sensor array which is exposed to the measurement light, converts the measurement light into electrical measurement signals, and processes them to form digital measurement data. The seat includes mounting structure for movably mounting the seat to an existing toilet bowl. The encryption module encrypts a communication pathway and transmits these items of information to the authentication server. The created label is sent to the server computer and stored in association with the plurality of management codes.