If a user purchased a subscription plan A, cancels later, then later repurchases, does the original_transaction_id change? There's no clear answer in Apple documentation, and no clear answer searching the web. We are using the original_transaction_id as a unique identifier for a subscription, and the subscription is associated with a specific user. If the original_transaction_id doesn't change at all, that means we'll never be able to allow a different user (say they switch the user on our app) to be associated with the new subscription period.