Cosmetic or dermatological system for performing a treatment, comprising: - a packaging and dispensing device comprising one or more compositions on the basis of which a product is delivered, the energy for dispensing the product being provided by the user directly, - an adjustment system coupled or able to be coupled to the packaging and dispensing device, to modify the amount dispensed and/or at least one property of the product dispensed by the packaging and dispensing device, - an electronic means for executing a program and either acting automatically on the adjustment system, or either for indicating to the user an action to be exerted on the adjustment system, so as to make the adjustment evolve in the course of the use of the device so as to comply with a predefined law of evolution suited to the treatment to be carried out, the program determining the evolution of the adjustment as a function at least of a quantity representative of the number of uses of said device, the electronic means being configured to detect the use of the packaging and dispensing device, and the adjustment being performed at least as a function of the number of uses thus detected, the electronic means comprising a switch sensitive to the actuation of a dispensing means, the switch advising the electronic means that a dose has been dispensed and the program taking account thereof, the switch being sensitive to pressure and disposed in a zone on which the user bears in order to dispense the product or the switch be actuated by the user when the latter presses a button controlling dispensing, or the switch be sensitive and detect a modification of the capacitance or conductivity of a predefined zone in the presence of a finger or the hand of the user in the vicinity thereof or in contact therewith, the program modifying the formulation of the product and/or the amount dispensed so as to comply with the predefined law. - a packaging and dispensing device comprising one or more compositions on the basis of which a product is delivered, the energy for dispensing the product being provided by the user directly, - an adjustment system coupled or able to be coupled to the packaging and dispensing device, to modify the amount dispensed and/or at least one property of the product dispensed by the packaging and dispensing device, - an electronic means for executing a program and either acting automatically on the adjustment system, or either for indicating to the user an action to be exerted on the adjustment system, so as to make the adjustment evolve in the course of the use of the device so as to comply with a predefined law of evolution suited to the treatment to be carried out, the program determining the evolution of the adjustment as a function at least of a quantity representative of the number of uses of said device, the electronic means being configured to detect the use of the packaging and dispensing device, and the adjustment being performed at least as a function of the number of uses thus detected, the electronic means comprising a switch sensitive to the actuation of a dispensing means, the switch advising the electronic means that a dose has been dispensed and the program taking account thereof, the switch being sensitive to pressure and disposed in a zone on which the user bears in order to dispense the product or the switch be actuated by the user when the latter presses a button controlling dispensing, or the switch be sensitive and detect a modification of the capacitance or conductivity of a predefined zone in the presence of a finger or the hand of the user in the vicinity thereof or in contact therewith, the program modifying the formulation of the product and/or the amount dispensed so as to comply with the predefined law.