You can check charges for your subscription and payments you have made through Billing & Metering component. Invoice data can be viewed in two ways.
In 'View Invoice' page, you can view invoices generated at each billing cycle. Online payments are available through Paypal if you are a Paypal account holder. For doing payments in a secure manner with Paypal click the Paypal button at the bottom of the invoice.
Interim invoice shows your current state of billing. This includes the amount brought forward and the amount accumulated for the period starting from last date on which bill is being generated to the current date.