Cellular memory is the local control mechanism for cellular function and integration with the roles played by adjacent cells and tissues of which it is a part. So within an organ, the mix of various cell types, each have a role and must work together to carry out the function needed for that organ whether it is one of metabolism or cellular production as for the immune system, or excretion as by the genito-urinary system and the distal alimentary canal, the nervous system, the heart, the lungs—all have a key role in taking in energy and applying the energy to useful work to allow diffusion of nutrients, and circulation of hormones, and signals for orchestration and control of things, and the coordinated interaction of all parts of the body to make things happen.
The very local level is done through cellular memory to keep the tissues in place to provide the overlay of instructions and feedback to know how big to grow, and then when to stop continuing to expand so that the organs have a defined size once the body reaches maturation, and then the organs are simply maintained for the life of the body, and so on. This is all done through the cellular memory, and so it has many, many key roles in the homeostatic regulation of things. The cells themselves are extremely complex involving thousands of biochemical interactions and many similar changes in gene expression, over the course of hours, to keep things running and to provide the information required to orchestrate each and every function needed by the cells.