I'm using ProfitWell to keep an eye on the revenue metrics, particularly since I don't have the domain knowledge as a technical founder to extract or even find them without serious work. The product is free, and their upsell product is non-intrusive.
The Stripe integration is superb, which makes ProfitWell almost hilariously easy to set up.
The UI was reworked recently, and is now (even) more clear and concise. The visualizations are understandable and instructive, and their customer support is excellent - I had a small hiccup with my Stripe plans and they resolved it immediately.
I need to keep track of my metrics. Actually, I need to find out which metrics are actually there to keep track of. ProfitWell allows me to browse current and historical data about my subscription plans, which led me to understand how well CLTV correlated with plan choice. That alone intensified my marketing efforts.