Suppliers of complex market offerings increasingly establish value-in-use management (VIUM) structures and processes to monitor and enhance the experienced value in use of their customers throughout the entire lifecycle of their offerings. Based on an exploration and a validation sample, this research develops and validates a measurement model for assessing VIUM implementation in B2B customer–supplier relationships. The exploration study focuses on the conceptual development, operationalization, and initial testing of a VIUM implementation index that captures the extent of suppliers' VIUM activities as perceived by their customers. The validation study assesses the index's criterion validity by analyzing its correlations with adjacent constructs, such as relationship value, relationship quality, and customers' intention to expand business with the supplier. The findings from both studies suggest an important role of VIUM in strengthening customer–supplier relationships. The newly developed VIUM implementation index serves as a valuable benchmarking tool for suppliers and offers actionable insights for customer segmentation and resource allocation, ultimately helping suppliers to improve their VIUM effectiveness.