how to check total number of customers utilized (Is totality, not per application)

how to check total number of customers utilized (Is totality, not per application)

Hi all,

How to check total number of customers utilized (Is totality, not per application) 
For example,
I have two applications
Application A (10 customers are using) and Application B (5 customers are using)
I wish to get the value of 15 customers.

I could not find a module to check the usage of customer of customer portal.
I am only able to find usage of user (internal user)

From the knowledge I knew, seem like we only can get the value via the Zoho Support.
Please assist.
Thank You