The present invention relates to a dispensing unit (3) for dispensing a substance into an external container (2). The dispensing unit (3) comprises a substance storage (4) with at least one compartment (11) and a connector part (5) in mutual rotational engagement with the substance storage (4). For at least one mutual rotational orientation of the connector part (5) and the substance storage (4), substance can flow from the at least one compartment (11) and into the external container (2) via the dispensing outlet (9) of the connector part (5). For at least one different mutual rotational orientation, substance cannot flow out of the compartment (11). The substance storage (4) and the connector part (5) comprise mutually engagable first and second engagement means (17,18), respectively, which are designed and arranged to ensure that the mutual rotation of the connector part (5) and the substance storage (4) follows a predetermined sequence of mutual rotations between stable mutual rotational orientations.
