If you credit card is about to expire, you should update your credit card details in Big Look to avoid the inconvenience of missing an payment and losing access to your course library. However do not worry if you do momentarily lose access to Big Look content as a result of a failed payment - once the credit card details are restored, all your courses will be recovered and you will not lose any progress you have made in those courses.
You can update your credit card details from the Billing tab of your account page.
To access your Billing details, you can click on the profile avatar link in the top right of the site header and select My Account. You can then select the Billing tab. From here you can update your saved credit card details.