Product retention is crucial for understanding the health of a business, as it measures the percentage of users who continue to use a product over time, indicating customer loyalty and the quality of customer relationships. For API-first businesses, retention is best measured by meaningful API activity rather than mere portal logins. Tools like Moesif facilitate retention tracking by allowing businesses to define key events, segment, and group data to derive insights into customer behavior. A retention report can identify whether a company's retention is optimal, dropping quickly, or lacks sufficient data history, guiding strategies for improvement. Enhancing customer retention involves refining onboarding processes, gathering customer feedback, and maintaining marketing efforts even after acquisition. Moesif offers features like Retention Analysis and Behavioral Emails to help businesses track and improve retention, ultimately aiming to boost customer loyalty and increase revenue.