A use history that at least associates a use subject identifier for identifying a user or a terminal device a user has used with a used item identifier, which is an item identifier for identifying an item used by a user, based on use information is stored in a use history storage section. Based on the use history, a degree of similarity between two item identifiers is calculated and using the degree of similarity, associated data causing a base item identifier, which is an item identifier of a base item, and an associated item identifier, which is an item identifier of an associated item similar to the base item to correspond to each other is created. A change value to change a point value managed for each use subject identifier is calculated.