Hi @toyaokeke,
The behaviour of the app subscription when cancelled depends on a number of factors, including how the subscription was cancelled, and what the replacementBehaviour for the subscription was set to when created.
If the subscription was cancelled due to the merchant uninstalling the app, the subscription is cancelled automatically, but the merchant can still re-install the app and the subscription will be valid until the end of the billing cycle.
When an app is uninstalled, Shopify automatically cancels the subscription. A credit isn’t applied to cover the cost of the rest of the billing period. Merchants can reinstall and use the app for the remainder of the billing period.
If they reinstalled the app and subscribed to a new subscription, when the new subscription is activated will depend on the replacementBehavior setting when creating the new subscription.
If the new subscription is activated before the end of the old subscription period, the next invoice will be prorated, with the merchant receiving prorated credits if the new subscription is cheaper, or having prorated charges applied if the new subscription is more expense than the old subscription.
If the subscription was cancelled manually with a appSubscriptionCancel mutation, the cancellation timing also depends on the replacementBehaviour set when the subscription was created.
Cancels an active app subscription, stopping future billing cycles. The cancellation behavior depends on the replacementBehavior setting - it can either disable auto-renewal (allowing the subscription to continue until the end of the current billing period) or immediately cancel with prorated refunds.
If you do cancel the subscription manually, and the replacementBehaviour is set to APPLY_IMMEDIATELY, you can provide the merchant with credits for the unused subscription time by passing prorated: true in the input of the appSubscriptionCancel mutation.
This will ensure your merchants don’t get “~45 days for $500 USD”, and instead get will get a credit for the 15 unused days of the old subscription.
Regarding the this feature isn’t currently available for your store error you’re experiencing.
Is this occurring on a Partner Development Store that was created in the Dev Dashboard, and had the Shopify Plus plan selected when creating it?
If so, this is likely a known issue that our developers are aware of and looking into further (see this thread for context).
If it’s not a Plus Development Store created in the Dev Dashboard from a Partner Account, then I would recommend reaching out to the Shopify Support team via the Shopify Help Center, while logged into the store this occurring on, and we can help you look into this further.