Dispensing assembly for dispensing a fluid or pasty product, such as a liquid or a cream, comprising: - a fluid or pasty product dispensing device which is an airless or atmospheric mechanical pump on a container, the said container containing a quantity of fluid or pasty product, - a push-button fixed on the pump and allowing the said pump to be actuated in order to dispense the product, characterized in that the distribution assembly is configured to adopt several successive operating states: - a first state referred to as a dispensing state, in which the dispensing assembly is able to dispense a first quantity of product contained in the container through actuation of the push-button, - a second state referred to as the blocked state, in which the dispensing assembly is prevented from continuing to dispense product despite actuation of the push-button, thus leaving in the container a second quantity of product referred to as the product reserve R, - a third state referred to as a dispensing state, which is achieved by an action of unblocking the dispensing assembly and in which the dispensing assembly is able to dispense product from the reserve through actuation of the push-button and in that the dispensing assembly comprises, inside the container, a device making it possible to create a product reserve R inside the said container, this device being created: - in the case of an airless mechanical pump, the container comprising a scraper piston associated with the airless pump, by a mechanical-stop system (9, 50, 55) situated inside the container and able to block the movement of the scraper piston, the said scraper piston also being situated inside the container, while maintaining sealing between the various elements of the distribution assembly in all the successive operating states, thus avoiding any pollution or contamination of the product contained in the container, assisted in that by the fact that the airless mechanical pump is fixedly mounted on the container in such a way that the user cannot remove it and by the fact that the product reserve R, like the first quantity of product N lies inside the one same container, - in the case of an atmospheric mechanical pump by a dip tube associated with the said atmospheric pump and having an emergent end situated at a height h from the bottom of the container, thus preventing product from being dispensed when the quantity of product remaining in the container measured from the bottom of the container is below or equal to the height h, and corresponds to the product reserve R. - a fluid or pasty product dispensing device which is an airless or atmospheric mechanical pump on a container, the said container containing a quantity of fluid or pasty product, - a push-button fixed on the pump and allowing the said pump to be actuated in order to dispense the product, - a first state referred to as a dispensing state, in which the dispensing assembly is able to dispense a first quantity of product contained in the container through actuation of the push-button, - a second state referred to as the blocked state, in which the dispensing assembly is prevented from continuing to dispense product despite actuation of the push-button, thus leaving in the container a second quantity of product referred to as the product reserve R, - a third state referred to as a dispensing state, which is achieved by an action of unblocking the dispensing assembly and in which the dispensing assembly is able to dispense product from the reserve through actuation of the push-button - in the case of an airless mechanical pump, the container comprising a scraper piston associated with the airless pump, by a mechanical-stop system (9, 50, 55) situated inside the container and able to block the movement of the scraper piston, the said scraper piston also being situated inside the container, while maintaining sealing between the various elements of the distribution assembly in all the successive operating states, thus avoiding any pollution or contamination of the product contained in the container, assisted in that by the fact that the airless mechanical pump is fixedly mounted on the container in such a way that the user cannot remove it and by the fact that the product reserve R, like the first quantity of product N lies inside the one same container, - in the case of an atmospheric mechanical pump by a dip tube associated with the said atmospheric pump and having an emergent end situated at a height h from the bottom of the container, thus preventing product from being dispensed when the quantity of product remaining in the container measured from the bottom of the container is below or equal to the height h, and corresponds to the product reserve R.