The document discusses relevant metrics for tracking a SaaS product across its lifecycle using the AARRR framework. It identifies metrics for acquisition like customer acquisition cost and traffic open rate. For activation, it suggests number of signups and subscriptions. Retention metrics include time since last visit and churn rate. Revenue metrics are customer lifetime value and monthly recurring revenue. Referral can be measured by net promoter score and virality. The document provides explanations for selecting each metric and why it is important to track.