Thanks for posting. It sounds like you may have received an email regarding the credit card listed as the primary form of payment on your account nearing its expiration date. If your card is expiring soon, you will want to update your credit card information by completing the steps outlined here (See Section on Updating or Removing a Form of Payment).
If you do not have an active credit card to use with AdWords, you may want to consider setting up payments via a bank account (direct debit). I want to clarify if you are using automatic payments and you do not have an active form of payment, you are at risk of the ads going off line. Let us know if there's anything else we can do to help out.