There is increasing interest in exploring how education abroad can contribute to enhancing sustainable behaviors. We adopted a functional approach to autobiographical memory to investigate the relationship between the directive function of study abroad memories (directing travel behavior, and directing life trajectory) and sustainable tourist behaviors (environmental, economic, social, and cultural). Global citizenship identity was tested as a mediator between functions of study abroad memories and sustainable tourist behaviors. A total of n = 493 study abroad alumni (2012–2022) from two U.S. universities completed an online questionnaire. Partial Least Squares Structural Equation Modeling was used to analyze the model. The results show that (1) the directing travel behavior function of study abroad memories enhances culturally and economically sustainable tourist behaviors; (2) the directing life trajectory function of study abroad memories enhances socially and environmentally sustainable tourist behaviors; and (3) global citizenship identity mediated the relationship between the directive functions of study abroad memories and sustainable tourist behaviors. Accordingly, we discuss the differences in adopting culturally and economically sustainable tourist behaviors versus socially and environmentally sustainable tourist behaviors, the application of autobiographical memory for study abroad program evaluation, and recommendations for future studies.