Maintenance contract needed for backups?

At one of our other sites, we have a server with BE 2012 (A) and another server with the agent (B). At the beginning of August, it stopped backing up the B server. It says it's licensed, but not installed (which it is) and there's no maintenance license. I'm confused.

The job failed with the following error: Before you can back up this source, you must purchase and install a license for the appropriate Backup Exec agent. See the Job Log for details.

Backup- [server]
License Violation

A Agent for Windows license is required for protecting remote servers with this edition of Backup Exec.

Please contact your vendor for information on protecting remote servers with this edition of Backup Exec.

V-79-57344-65084 - Before you can back up this resource (\\[server]\D:), you must purchase and install a license key for the appropriate Backup Exec agent.

For information about how to obtain a license key, go to the following URL: 

http://www.symantec.com/business/backup-exec-for-windows-servers

A selection on device \\[server]\C: was skipped because of previous errors with the job.

A selection on device \\[server]\System?State was skipped because of previous errors with the job.

Thanks