The invention relates to the application of liquid active substances with the aid of a portable spray device. The subject matter of the present invention is a system comprising a portable spray device and a replaceable cartridge that contains an active substance concentrate. The invention also relates to a method for applying a liquid active substance formulation. In addition, the invention discloses a replaceable cartridge that has a memory unit in which information is stored relating to an adjustable dilution ratio for the active substance concentrate contained in the cartridge. The invention also relates to a spray device comprising a control unit that can read out a memory unit of a cartridge attached to the spray device and, on the basis of the read out information, adjust a dilution ratio for the active substance concentrate contained in the cartridge.
