The irreversible electro-optical response (memory effect) of 'liquid crystal-aerosil' suspensions under the influence of an electric field is investigated. Thereby, the influence of the aerosil concentration on the efficiency of the memory effect is studied. The experimental results are discussed in the frame of a model where the filled nematic is considered as a system of aerosil agglomerates in a liquid crystal matrix stabilized by the forces of liquid crystal orientational elasticity.