In order to prevent interruptions in service, you must make sure your credit card with PayPal is up-to-date AND that you update any subscription's associated to that credit card.
For failed subscription's due to expired CC's follow these steps:
1. Log in to your PayPal account.
2. Click Profile near the top of the page.
3. Click My money.
4. Click Update beside "My preapproved payments".
5. Select the merchant whose agreement you want to change under "Merchant."
6. Click Change under "Payment Method".