In this brief note we discuss some methodological consequences of studying memory phenomena i systems where the level of mental activity in sufficiently sophisticated to have conscious memories. As it is characteristic of scientific praxis, the facts and procedures in the study must be repreatable without any restrictions in principle or methods. We discuss some aspects of a theory of the physical systems with memory, and we indicate a way to characterize the act of consciously remembering in intelligent systems. We then show the importance of behaviour theories that use only physical processes as intermediate explanatory elements to build a model with the necessary complexity. We finally show how behaviour theories that use only physical processes as intermediate explanatory elements are particularly suitable for giving a unifying point of view.