To achieve a technological breakthrough in the creation of high-speed PCM cells, it is necessary to understand the nature of the switching effect of stable states and study the properties of the materials used for the working layer of a memory cell. The study of crystallization kinetics requires knowledge of the fundamental thermal properties of both crystal and amorphous states. If to consider all the chemical compounds tested for possible application in PCM memory, the metal nanoclusters of a relatively smaller size are of a special interest to analyze them for this task. The applicability of using individual nanoclusters of Ag as unites of storage of data bits in nonvolatile memory devices, the store capability of which is based on the principle of the phase change of the state of the carrier of information, has been estimated. Therefore, with the help of the molecular dynamics method on the basis of the TB-SMA potential, the simulation of melting-crystallization processes of Ag nanoparticles (D ≤10.0 nm) has been performed. The influence of various conditions of crystallization on the formation of the internal structure in Ag nanoclusters is investigated. The limiting size of Ag nanoparticles is determined, for which a structural "orderdisorder" transition necessary for the data recording is still possible. It has been concluded that the best material for the memory cells, the store capability of which is based on the occurrence of phase transitions, is Ag nanoclusters with a diameter of D ≥ 8.0 nm.