Developer License: Developer License is for development. Every developer working on TWAIN programming needs a Developer License. For example, if you have 3 developers working on Dynamic Web TWAIN, you need 3 Developer licenses.
Web Server License: Web Server License is for Web server deployment. Every Web server deployment needs a Web Server License. For example, if you have 3 developers and 3 Web servers to deploy on, you need 3 Developer licenses and 3 Web Server Licenses. After you deploy Dynamic Web TWAIN properly on your web server, the number of end users is not limited.