System comprising a nebulizer configured to nebulize a fluid from a replaceable container and the container containing the fluid, wherein the nebulizer comprises: a housing and a housing part configured to be detached from the housing to open the housing in order to insert the container and in order to replace the inserted container; an indicator device configured to count or indicate the number of uses performed or still possible with the container, wherein each of said uses consists of operational steps necessary for the nebulization of a preferably metered dose of fluid from the container when the container is inserted in the nebulizer and the housing is closed; and associated to the indicator device, a locking device configured to block the nebulizer against further use with the container in a locked state when a predetermined number of uses has been reached or exceeded with the container, and wherein the indicator device is configured to mechanically actuate the locking device to cause the nebulizer to enter the locked state when the predetermined number of uses has been reached or exceeded with the container; and wherein the container comprises a control device configured to indicate an unused state of the container, wherein the control device comprises a control member which is moveable from a first position to a second position, wherein the control member being in the first position indicates the unused state of the container and wherein the control member being in the second position indicates an already used state of the container, wherein the system is configured such that the control member of the control device is moved from the first position to the second position when the container is used for the first time with the nebulizer, wherein the control device is configured to reset the indicator device when the container, with the control member in the first position, is inserted in the nebulizer in the locked state and the nebulizer is closed, wherein the resetting comprises the control member of the control device actuating the locking device indirectly via the indicator device so that the locking device is unlocked by the control device via the indicator device and the nebulizer is unblocked by unlocking the locking device, wherein the control device or control member is constructed such that a predetermined mechanical control force has to be applied to the control member to move the control member to leave the first position, wherein the predetermined mechanical control force is set higher than the mechanical force that the control member has to exert to reset the indicator device. a housing and a housing part configured to be detached from the housing to open the housing in order to insert the container and in order to replace the inserted container; an indicator device configured to count or indicate the number of uses performed or still possible with the container, wherein each of said uses consists of operational steps necessary for the nebulization of a preferably metered dose of fluid from the container when the container is inserted in the nebulizer and the housing is closed; and associated to the indicator device, a locking device configured to block the nebulizer against further use with the container in a locked state when a predetermined number of uses has been reached or exceeded with the container, and wherein the indicator device is configured to mechanically actuate the locking device to cause the nebulizer to enter the locked state when the predetermined number of uses has been reached or exceeded with the container; and wherein the container comprises a control device configured to indicate an unused state of the container, wherein the control device comprises a control member which is moveable from a first position to a second position, wherein the control member being in the first position indicates the unused state of the container and wherein the control member being in the second position indicates an already used state of the container, wherein the system is configured such that the control member of the control device is moved from the first position to the second position when the container is used for the first time with the nebulizer, wherein the control device is configured to reset the indicator device when the container, with the control member in the first position, is inserted in the nebulizer in the locked state and the nebulizer is closed, wherein the resetting comprises the control member of the control device actuating the locking device indirectly via the indicator device so that the locking device is unlocked by the control device via the indicator device and the nebulizer is unblocked by unlocking the locking device, wherein the control device or control member is constructed such that a predetermined mechanical control force has to be applied to the control member to move the control member to leave the first position, wherein the predetermined mechanical control force is set higher than the mechanical force that the control member has to exert to reset the indicator device.