how to detect the renewal status in apple auto subscription development?

Question

there is a way if the server verify the receipt the apple will return the latest_receipt_info which contains the expires_date of auto subscription.But what time and what way to do this check? everyday the server to do this check or the app to do this when it's opened,should I always take the first buy receipt to post http://buy.itunes.apple.com/veriryreceipt for get the latest_receipt_info?

https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/StoreKitGuide/Chapters/Subscriptions.html

is there a good way to check the renewal status?