The relationship between students and higher education is seen to have become increasingly transactional. We approach the study of the student-HE relationship in a novel way, by focusing on students' behaviour post-university, rather than on student narratives. Conceptually, the article builds on multidimensional views of student engagement and the differentiation between psychological transactional contracts -- where students who achieve better academic results are more likely to donate -- and relational contracts -- where students donate more following engagement in social experiences. Making use of longitudinal data on donation behaviour from over 50,000 alumni from an English university over two decades, we find that while students who get better degree outcomes are more likely to donate, the association between participation in social experiences and donations is much stronger. This questions prevalent transactional models of HE and underlines the limitations of purely consumerist views of the relation between students and higher education institutions, even in the marketized UK context.