If a customer pays using AppExchange Checkout, how can I ensure that paid features are immediately accessible?

When a customer makes a purchase using Checkout, the license records in the License Management App are updated, but feature parameters aren’t. To update feature parameters that you've created, define an Apex trigger in your License Management Org (LMO). Have the trigger fire when the license record is updated. In your trigger code, update the LMO-to-subscriber feature parameter.