Please find below steps to check usage :

1) Login to the EMM panel
2) Go to Reports->Monthly Billable Counts
3) Option can be selected to fetch report for “Past 3 Months Reports” or “Past 12 Months Reports”
4) Provide the date range and click on Search
5) Details will be displayed. Click on “Sent” count
6) A new pop-up will open for the selected date range
7) Download option can be seen at the bottom. The report will be downloaded for the same.
Screenshot for same