Today we are announcing the availability of License Included (LI) Amazon Machine Images (AMIs) for Windows Server version 1903 for Amazon EC2, providing customers with an easy and flexible way to get up and running with the latest version of Windows Server Semi-Annual Channel release. Windows Server 1903 adds features that are best suited for use cases that involve building modern container-based Windows applications, such as enhanced Kubernetes support.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/05/announcing-windows-server-version-1903-amis-amazon-ec2/