One of the key elements of a company’s success in the market and its growth is nurturing customer relationships. This paper presents research to identify Legimi JSC’s customer groups and define potential actions to prevent churn and increase revenue. For this purpose, customer K-means segmentation methods with the use of RFM (recency, frequency, monetary) and CLV (Customer Lifetime Value) models based on customers’ engagement with Legimi service and their spending were developed. The authors applied a new approach to the problem of determining user-generated costs by determining customer involvement in terms of time spent on reading and the number of books read.