Hi Debendra, that message means you do not have the licenses to support managing an additional device. When using ExtremeCloud IQ, you must purchase a number of licenses equal to the number of devices you are managing within ExtremeCloud IQ.
To view your current licenses, you'll want to click on the silhouette icon in the top right corner> Global Settings> License Management (left hand side menu under the Administration header)> here you can see how many licenses you currently have and when they will expire.
To purchase a new license, you'll want to speak with our sales/services team. If you're not sure who to reach out to for your sales contact, please let me know generally where you are located, and I will find a local services engineer to speak with you about licenses.