The software quality assessment can be performed using the analysis of quality components established in ISO/IEC 25010. Usability is a quality component directly related to the system’s user experience (UX). The user’s success in the interaction depends on the user’s performance in the actions determined to deliver the product value. Studies point out the Customer Success (CS) methodology as a valuable tool for evaluating systems since it uses metrics to measure CS when using a software product. The use of CS metrics to evaluate software components is increasingly being implemented in systems development. However, the metrics for CS are not fully defined, and there is also scant research linking to the software’s quality components. In this scenario, we present a method based on CS metrics for software product usability assessment, a quantitative approach to provide success indicators in the context of SaaS. The main CS metrics and their application in different coverage contexts are unveiled. In our proposal, the Component Usability Index (UCI) and Software Usability Index (USI) arise as indicators of customer success, owing to their relationship with the standards usability components that influence the user experience during interaction.