If you're not checking your customers' expired cards, you're losing money
At Ztory, our subscription service for magazines, we've seen out that about half of our unsubscribes are due to declined charged on our customers' credit cards. To combat this, we just added a trigger to send an email telling a customer to update their payment details when we detect that their card is about to expire.
With this small action, we've seen a 70+% email opening ratio and about 15% renewed cards, which means a lot of reclaimed revenue we would've lost by declined charges:
Related to this, my personal credit card is about to expire, but I've yet to receive a notification from any of the services that have it (I'm looking at you, Paypal, Amazon, Google...) to update it.
I guess I will have to do it by hand, and that will mean giving a hard look to all the subscription services that I have, and surely canceling more than one by simply by not updating the card there. Hopefully we're making our users' lives easier at Ztory by giving them an auto-login link straight on their email to do this :-)