You can update the credit card information on your account from the following URL: https://www.linksalpha.com/account/subscribe_cc_info.
LinksAlpha.com supports PayPal as a payment method for its monthly subscription payments. In case you have received an email from LinksAlpha.com stating that your monthly subscription was not processed, you will have to update your credit card information in your PayPal account. Once you do that, PayPal will try to charge your account again in 5 days from the date of last unsuccessful attempt.
If you want to change the PayPal account that you are using, first switch to the Free Account and then upgrade to the Pro Account again. You can manage this change from your Account page.