In cloud-native environments, service model selection is critical for optimizing both operational and economic outcomes. This study investigates the migration from a serverless Function-as-a-Service (FaaS) model, specifically AWS Lambda, to a monolithic solution deployed on Amazon EC2. We examine this transition to evaluate cost savings, performance improvements, and architectural considerations across various scenarios. Our findings indicate that migrating to Infrastructure-as-a-Service (IaaS) can offer notable cost benefits in specific contexts, though it also introduces infrastructure management requirements. This work provides insights into migration decisions and practical considerations when transitioning from FaaS to IaaS-based models.