You have 3 sources for statistical information:

First of all the, on the Right-Click Desktop Status Menu, you have access to Quick Status that shows you how many SMS’s sent and received since last midnight. From the same menu you can access the full SysManSMS HTML Status page which shows you the same, but also includes a total count since last restart of the server.

You also got a file in

…\SysManSMS\GSMserver\OUTPUT called computername_SysManSMS.csv

that contains some statistical counters to be used from other applications.
The last possibility you got, is to turn on the Accounting file. This is written to same local OUTPUT folder, and is called Accounting.csv. You turn it on and select accounting options, in the Accounting.ini file found in the GSMserver folder. You may read more about accounting in the User and Developers Guide.