In order to check your current subscription status, you'll need to access your Billing Settings page. From there, you can:
View your current plan
From here, you can see everything there is to know about your current plan, and you can change your payment method, if you like. If you don't see this section, you don't have a Pro subscription (yet).
Upgrade to a different Pro plan
Just below your payment plan, you'll see an overview of the other available upgrade options for your Paste team.