Physical actions are the result of the interactions between current external stimuli and a lifelong history. Memory is a crucial part of a fully functional nervous system giving rise to a phenomenal level of features such as adaptability, plasticity and survival systems.
Neurons in the brain are connected in vast networks and this connectivity endows properties that are not found in individual neurons. For example, memory has been studied extensively and is the result of presence of long timescales at the network level. If the memory of a stimulus is beneficial for a long time after it ended, long timescales are needed.
Further details: Long timescales support neuron activity and the amazing human brain