Microsoft has a centralized billing system for many of its online services. If you’re using Windows Live OneCare, you can view the status of your subscription at http://billing.microsoft.com/. Log in with your Windows Live ID – the e-mail address and password used to install OneCare.
If you click on OneCare (or other services listed), you’ll see the renewal date. If it’s scheduled to expire in the next couple of months and you plan to keep using it, go ahead and click on “Renew.” You won’t be billed until the expiration date.
While you’re there, check your credit card information and bring it up to date if necessary. OneCare is currently wrestling with a bug that causes it to complain if the credit card on file is past its expiration date, even if the OneCare subscription itself doesn’t expire for months.