Research shows that in university education programs, students’ motivation decreases over time, which is associated with indicators of reduced academic success, such as student dropout rate. Consequently, researchers have analyzed motivation change and explored the options available to universities to maintain a high level of motivation among students. Using Person-environment fit theory, our research suggests that perceived support offered by lecturers and instructional quality influence students’ subject interest. We conducted a longitudinal design of 823 participants from Baden-Wuerttemberg Cooperative State University and estimated a latent change score model using data collected between the participants’ first and second academic years. Our findings suggest that perceived support from lecturers mitigated the decrease in subject interest. Moreover, our results support the hypothesis that universities can attenuate the decreasing change of subject interest from students. Our findings are contextualized with reference to contemporary research in the field and we offer practical suggestions for maintaining high motivation among students.