DLP feature vs Enterprise CAL

Hi,

I am trying to test the DLP feature.

My install: Exchange 2013 SP1, Enterprise Server License.

Client: Outlook 2013 Pro ( can work with EX13 for DLP)

Standard CAL license.

I tried to create a DPL test rule. It doesn't work.

It said that I need Enterprise CAL ( ECAL). I don't see where I can "Install" the Enterprise CAL. I want to test this feature before spending $10K on the Enterprise CAL. Can someone shed a light. ALL googling come up with the different between SCAL and ECAL. 

I ran this comment and it shows that all users are using SCAL: Get-ExchangeServerAccessLicenseUser –LicenseName “Exchange Server 2013 Standard CAL”