Development of composed services requires a continues adaptation of the composed service to the changing environment of offered services. Services may no longer be available or may change performance characteristics, price, or quality of service criteria after they have been selected and used in a composition. The replacement of such a service requires a good understanding why this service got selected in the first place. This is hard to accomplish as it is known from software maintenance. Therefore we propose an approach where the conceptual task implemented by a selected service as well as the relationship between task and selected service is explicated and maintained during the complete life cycle of a composed service. This covers the design of the composition, derivation of service search criteria, and the execution of the composed service. The approach has been validated by an implementation in the Service Composition Studio (SERCS) supporting the iterative development of composed services.