When creating and/or editing subscriptions, you can plan for future changes in the subscription. This can be changes such as ramp-ups, discounted initial period followed by full price, etc. Read more about how to set up common subscriptions with periods here.
When creating a subscription with future changes, these are applied by adding periods to the subscription. A subscription can contain multiple periods, where each period lasts during specific dates. Planned future periods are listed under the heading "upcoming changes", whereas periods that have already passed in the subscription are listed under "passed changes".
For each period, you can quickly see how the period will change in annual or monthly value. You can also see if the period itself has a termination date or is a renewal period. If you want to see and compare what products the periods contain, hover on the product icon to see the products and amounts.
To see the full subscription, click on the row and the period will be opened up.