Event-based billing is revolutionizing SaaS monetization by shifting from flat subscription fees to a consumption-based pricing model that aligns more closely with customer value. This approach, exemplified by companies like HubSpot and Stripe, involves charging customers based on their actual usage of services, such as API calls or data processing, similar to utility billing systems. Key components of event-based billing include real-time event capture, aggregation into billable metrics, pricing calculations, and invoice generation. This system allows for flexible pricing models, such as tiered or volume-based pricing, which can encourage higher consumption and optimize revenue. Despite the technical complexities and challenges related to data accuracy and regulatory compliance, event-based billing offers significant benefits, including improved customer retention, transparency, and competitive differentiation. The model also supports better unit economics and customer satisfaction by ensuring that pricing reflects the value delivered. Modern billing platforms, like Lago, facilitate the transition to this model through high-volume event processing and integration capabilities, positioning usage-based billing as the future of SaaS monetization.