Yes, you are correct that Azure Functions charges based on the number of requests made to it, whereas Azure App Service charges based on the number of hours the app is running. In the case of an enterprise app with 100,000 users, you'll likely have a large number of requests being made to the Azure Functions, which could result in high costs if the function is triggered frequently or around the clock. In this case, you may want to consider using Azure App Service instead as it charges based on the number of hours the app is running, which could be more cost-effective for you in the long run. It's worth mentioning that the choice between Azure Functions and Azure App Service ultimately depends on the specific requirements of your enterprise app. You should consider factors such as scalability, ease of use, and performance when making your decision. It might be helpful to run cost simulations.