Knowledge based computer systems may be designed for many environments, demonstrating different patterns of behavior. Though the inferences obtained may be similar, the use of the inferences may require some supplementary information directly related to the subject domain properties. For such complex cases a concept of retention is proposed in this paper intended for applications to a wide variety of situations, where an intelligent system may depend upon complex external conditions. Examples of systems designed by the authors are provided that support this new concept. In conclusion, an attempt to formalize this concept in the language of Category Theory is provided.