It is commonly established that simple action phrases, such as “open the book” or “break the tick”, were retained better when participants were instructed to perform the actions themselves than they learned the phrases by listening or reading. The excellent memory performance for subject-performed tasks (SPTs), compared to verbal tasks (VTs), has been called the SPT effect or enactment effect. Although a great many of researches had focused on the enactment effect as well as four theories had been proposed to explain the enactment effect, there was no unitary model to explain the empirical findings. The purpose of this article was to present the development of the four explanations on action memory and to address the enactment effect from the perspective of integrating the process procedures as well as the process system. The first theory was the nonstrategic theory. The researchers proved that action memory might be mediated by automatic processes. However, as the research moved along, critical words were put forward against the nonstrategic view. Now most researchers considered that the pop-out mechanism contributes to the free recall in SPT. Next, researchers put forward the multimodal view which considered the visual modality, the auditory modality, the tactual mode, even the olfactory as well as gustatory modes might be involved in specific SPTs. This multimodal notion was later extended a dual code view which stated that physical properties of SPT were encoded non-strategically, whereas the verbal components were encoded strategically. However, the argument of the dual code hypothesis by the proposers appeared contradictory results. So, most researches concentrated on the multimodal view other than the dual code hypothesis for the SPT effect. Then, the third theory - the motor encoding view was proposed by Engelkamp and Zimmer who argued that the memory traces were enriched by motor components in addition to verbal, visual, and conceptual components. The motor encoding was the key for enactment effect. As research continued, most researches demonstrated there may be a motor system for handling the motor information. Finally, we analyzed the episodic integration view which differed quite radically from the above three theories discussed. According to this view, the encoding of action events was wholly strategic and enactment increased the degree of self-involvement for subjects. Enactment increases the integration in three ways : (1) a better integration between the environment and the subject; (2) within-event integration; (3) between-events integration. Enactment encoding was considered the “glue” that cemented the components of actions into a memory unit or into closely connected memory units. In summary, we analyzed the theories and found that the nonstrategic view as well as the episodic integration view mainly concentrated on the memory process procedures, and the motor encoding theory as well as the multiple codes view mainly focused on the objects of the processing. Both of them paid attention to the one and ignored the other. So integrating the process procedures and the process objects may give us a window to explore the processing mechanism of SPT effect in action memory.