When two Products share the same Plan within the same Store, you can allow customers to move between the subscription Packages that are a combination of Products using that same Plan.

Under Store Settings > Miscellaneous, you can:

• Allow/disallow customers to upgrade their current subscription to a different Package using the same Plan
• Allow/disallow customers to downgrade their current subscription to a different Package using the same Plan

• Merchants can upgrade/downgrade a subscription by clicking on the corresponding link from the subscription details page.
• Customer can do the same in the Customer Center (if allowed, as mentioned above)
• API: the SubscriptionBridge API will soon allow you to trigger an upgrade/downgrade