After updating an AWS AMI for Arc (or previous releases such as ArcESB and RSSBus Connect) to support IMDS v2, the licensing check for the instance will fail, and you will see an error in the Licensing or About page, depending on the version:
Licensing error: version. Could not find a valid license for using version on this system.
Licenses leased through the AWS Marketplace that are not the CData Arc BYOL (Bring Your Own License) AMI use an algorithm to check their licensing against the AWS servers that is not compatible with IMDS v2.
If you have updated to IMDS V2 on one of these images, you will need to roll back to IMDS v1 to restore your license.