Lync 2013 now provides a useful PowerShell script for checking your Lync 2013 CALS

You can search by

UserBased / Device Based, Enterprise, Standard or Plus CALS.  specify Start / End Dates and daily usages as well.

An Example can be found below that also outputs to a text file :

Get-CsClientAccessLicense -MonitoringDatabase “<Monitoring  SQL Server FQDN>” -LicenseName “Standard” -LicenseBasedType “UserBased” -StartDate “01/08/2013” | Out-File c:filename.txt -width 120

For more information please see