There are a couple of places in your account to see what your current subscription is. Probably the easiest is to click on the Account icon in the top right corner. You'll see a menu and at the top, highlighted in purple, is your current plan.
We'll tell you if you're using the Free, Basic or Pro plan and how many email addresses you can mail to.
Or, from that same menu click the Billing History option to see your current plan, any charges in your account and an option to upgrade if you need to.