To check the data for the Pocket WiFi, simply access http://192.168.1.1. when the page loads completely, click Data Usage and then View Details (top of the page). The link will bring you to a page where you can see Current data usage or History (displays the total data {upload and download}). The interface of the software also displays total data usage for a session.
Note: If you access the page on a smartphone, tap on View Classic, then follow the above instructions.