When you import a Windows VM from on-premises to AWS, the licensing terms for Windows and Client Access Licenses (CALs) might vary depending on the licensing model you previously used and how you plan to run the VM in AWS.
If you had a volume licensing agreement with Microsoft, such as Software Assurance, which allows for mobility of Windows licenses, you might be able to bring your existing Windows licenses to AWS.
AWS provides a "Bring Your Own License" model for certain software, including Windows Server instances. This means if you have valid licenses for Windows Server, you can bring them to AWS and use them on instances that support this model.