If you are paying for your Funimation subscription with a credit card, you can update the current credit card or add a new credit card directly in Funimation.com. Log in, go to "My Account", and click "Subscription." Then click to expand the "Billing Information" section. Select the payment method marked as "Default Payment Method" and then click on "Edit". Make your changes and then click on "Save". If you would like to add a different credit card, click on "Add a New Card", fill out the form, and save it. You can then mark this card as "Default Payment Method" to have that card charged for your subscription instead.