Retention in consumer startups can be challenging; for Monzo, we defined an active user as someone who completed at least one financial transaction per week to measure engagement effectively.

Measuring revenue churn is critical for subscription-based businesses, as it helps you understand how many customers are leaving your service.

For Monzo, users who added three friends to their account during signup retained significantly better than those who did not, demonstrating the impact of social features on user engagement.

Organic growth, which is growth that doesn't require payment, is often neglected by founders. For example, at Monzo, we reached a million customers before spending on direct marketing or advertising, primarily through virality and network effects.

Churn rate is crucial to track; understanding why customers leave can help improve retention and inform future pricing strategies.

You can derive monetization as a North Star metric by tracking monthly recurring revenue for subscription businesses or transaction values for e-commerce.

When you charge more, you can achieve higher margins, allowing you to invest more in customer acquisition and build a stronger competitive moat.

It's essential to track unit economics closely, especially in businesses with thin margins, to optimize costs and focus on advertising channels that attract high-revenue, low-cost customers.

Monetization metrics should reflect how much revenue you generate weekly, comparing it to previous weeks to gauge growth.