Abstract: A method is claimed comprising the following steps: setting up an association of the points of sale by means of associating said points of sale and admitting natural and legal persons as the association members, forming the association members database at the central control unit of said association, making available a personal data medium to each association member, said data medium containing privilege purchase information, and forming communication channels communicating said central control unit with each of the associated points of sale, providing each associated point of sale with a unit for receiving and processing information contained on each personal data medium, making available the personal data medium to a potential customer by an association member, allowing a discount according to the privilege purchase information contained on the data medium to the potential customer in case of a transaction made by him at the associated point of sale, subsequent paying an appropriate remuneration to the asso