Monitor Pro as an OPC client

Greetings to you all,

I had used Monitor Pro as an OPC server before, The OPC client application is a custom application.

I knew that each OPC client required a "CAL" license.

Now, We need to connect different SCADA system to Monitor Pro. we think of making Monitor Pro as the OPC client. will it required "CAL" ?

Any other thoughts?

Thanks in advance
Regards,
Ayman