Measuring the success of in-product experiences involves setting specific goals for user interactions and identifying key metrics to track. The first step is to find the adoption bug, which refers to any negative event within the user journey that can prevent users from taking key actions or adopting important features. Next, establish what metrics you want your experiences to impact, such as feature activation, customer retention, or NPS score. Experimentation through A/B testing and regression analysis is crucial for creating successful in-product experiences. Finally, continuous iteration and assessment are essential for the success of in-app marketing efforts.