Under Settings => Billings, click on the Manage Subscriptions button.
From this menu you can add or edit the following:
Account information - personal information and/or company information.
Billing and shipping addresses
Payment methods - credit card details
Billing history - view and download historic invoices
To make any changes to your subscription, click on the large white subscription button.
From here you can:
View a breakdown of your subscription charges
Change your shipping address
Edit your subscription
Cancel your subscription