Hi Friend,
Don't worry.
It is possible to avoid this reboot by deleting the evaluation license key either from CLI or WebUI.
follow these steps to delete the eval license.
CLI command:
use show license to display all the licenses and copy the license to delete.
license del <evaluation license key>
For example:
license del tPOIJ8Za-IkuyQLE0-01LvoC8h-icWgQt8H-uNPz4V8e-pKU
Key disabled; temporary keys cannot be removed.
Please reload the switch for the key removal to take effect.
over GUI :
Browse to Configuration > Controller > Licenses and delete the evaluation key.
Manually reloading the switch after deleting the key removes the license-related configuration. This reboot can be scheduled for a maintenance window.
Don't worry about rebooting, you can schedule downtime and reboot inorder to remove the key completely.
Hope you got your answer,
Please feel free for any further help on this.