Official comment
If you're selling a subscription product, you should check out the subscription and payment plan details. There are two main places for this. The first is within a specific contact record under the "Purchases" tab, all the way at the bottom. The second will show you all of the upcoming charges for all Contacts with open orders. This is all kept in one Sales Report that you can find under Sales > Reports > Open Orders.
This report shows you details such as the product name, the contact (name and email), the next payment amount (which can be broken down into tax, shipping and next charge), next payment date, etc. If you do not see the columns you want, you can add them by hovering over the plus sign in the top right of the report.
For more information, check out our Knowledge Base article on Sales Reports and our Knowledge Base article on Managing Transactions.