Too Long; Didn't Read
Churn rate, MRR, LTV, CAC, and Engagement are some of the most important SaaS metrics you should be monitoring. The main challenge is to "retain" the user before the bulk of income from them becomes more than the investment in marketing to attract that customer. As a rule, it is considered a healthy one-business-business rule, which is lower than the CAC three times more often than the LTV ratio. For example: if your customer churn is 3%, it means that the user will "stay" with you for 33 months: 1 / 0.03 = 33.