Step 1 - Go to https://LegalFormsGenerator.com/login and log in. 

Step 2 - Go to https://LegalFormsGenerator.com/support and scroll down to "How do I update my credit card information for my Website Legal Forms Generator Pro Plus Subscription?" 

Depending on if you originally paid using PayPal or a credit card (via authorize.net) you'll be show the appropriate update information if you are logged into https://LegalFormsGenerator.com