As businesses grow, the initial billing solutions like RevenueCat may fall short, especially for companies with complex pricing models such as B2B SaaS or those requiring an API-first architecture. Alternatives like Stripe Billing, Chargebee, and Lago offer advanced features to address these complexities, including faster time-to-cash and reduced billing errors. The choice of a billing platform is vital and should consider factors like billing model flexibility, integration capabilities, and analytics depth. Modern billing strategies often go beyond flat-rate subscriptions to include usage-based and hybrid models, necessitating platforms with robust event-ingestion engines. Additionally, a seamless integration with existing systems, high-quality APIs, and data portability are crucial for developer experience and preventing vendor lock-in. Advanced analytics for real-time insights, paywall A/B testing, and cohort analysis are essential for optimizing revenue. For mobile-first apps, Adapty offers advanced monetization tools, while Stripe Billing and Chargebee excel in versatile, complex subscription management. Lago stands out for event-driven, usage-based billing with an open-source, developer-centric approach, providing scalability and accuracy. Migrating billing systems involves careful data export, parallel integration, and historical data import to ensure continuity and reliability.