If you are seeing notifications like these about your license expiring, read on to find more about it:
Historically, Adobe issued serial numbers with our apps (i.e. Creative Suite, Creative Cloud for enterprise, Acrobat XI, Acrobat DC) to customers on Enterprise Term License Agreements (ETLAs). These serial numbers do have an expiration date. Once the expiration date has passed, the product will no longer work so it is important to plan your migration before your serial numbers expire. Ensure your end users have continued access to their Adobe apps and services.
Learn how to use the AdobeExpiryCheck tool to check if the volume serial numbers have expired or are expiring soon. If they have expired or are expiring soon, it is recommended that you re-serialize with a new serial number.