For subscribers who purchased on the web (and NOT mobile):
Click "Manage billing"
Then, select the specific payment you want to view to access the invoice and receipt for it.
Click on Download Invoice or Download Receipt, as applicable.
For subscribers who purchased on our mobile app:
Go to the Settings app on your mobile device. Then click on your Apple ID > Media & Purchases. Click "View Account" and then tap on Subscriptions to cancel or tap Purchase History to view your payment receipts.