The final article in a series of works on creation of ion‐molecular models of memory is dedicated to the entropy factor. The authors examine the correlation between information and entropy. They introduce an entropy equivalent in the specificity of memory (by I. Prigozhin). The memory system is considered markedly nonlinear and non‐equilibrium. The article contains a general conclusion to the series of works. The entropy factor is, from the position of bio‐physic‐chemistry, an important aspect of memory, as a higher form of functioning of the organism, including human organism ‐ in the first place. It is possible to allocate to factor the actual memory several types of entropy, instead of one integrated, as for example in the case of the classical thermodynamic processes. Moreover, the thermodynamic entropy, as a defining static processes, virtually ignored in ion‐molecular memory model (Boltzmann entropy). Here more significant is the consideration of the role of information Shannonʹs entropy. And another important point: to evaluate the entropy of systems with non‐equilibrium processes, which undoubtedly applies to the memory, I. Prigozhin proposed to use the sum of the elements of the correlation matrix, the diagonal members which are set in accordance with probability, and extra diagonal ‐ correlations. The authors use it in the estimation of entropic characteristics of ion‐molecular memory model. I.e. on the basis of proposals Prigozhin, the authors introduce entropy equivalent, which corresponds to the provisions of non‐equilibrium thermodynamics and the requirement for orientation changes in two of its components, that allows to estimate the partial contributions of both types of entropy to the total entropy of memory.