If you want to access information about system usage, subscription periods or payments, navigate to System, select System usage, and then Current usage from the menu on the left.
You will see a screen with information and statistics on your current subscription. These include subscription period, name of the subscription plan, limits, additional payments, and the current usage information, e.g. number of contacts in your database and number of emails you have sent to them.
You can also use the red additional limits button to add limits.