To use NetBackup for Exchange, add a valid license key for it on the master server. More information is available on how to add license keys.
See the NetBackup Administrator's Guide, Volume I.
In a NetBackup cluster, add the key on each node where the NetBackup server is installed.
More Information
NetBackup server and client software requirements for NetBackup for Exchange
Exchange server software requirements for NetBackup for Exchange
Requirements for mailbox backup and restore operations
Requirements for Exchange in a cluster environment
Configuration and licensing requirements for Exchange snapshot backups and restores