All your subscription information can be found via Account>My Subscription, including remaining reference allowance, start date, expiration date, and active/inactive status for all subscriptions associated with your account. 

You will first see the details of your current subscription, including paid and unpaid overage charges:

To view your Subscription History, scroll to the bottom of this page. If you have several subscriptions associated with your account, you can choose how many to display per page.