If you have a Grandfathered Membership, Property Rights Subscription, or Newsletter Subscription (found under the "Subscriptions" section on the "My Account" page) you can update your billing info as follows:
1.) Login to MassLandlords.net and click the "My Account" section which is found at the top right of any page
2.) Scroll down and find the section that says "Subscriptions"
3.) Look to the right of that section - there will be a small black link that says "Update Billing Details" (it is somewhat small and can be easy to miss - we're hoping we can change this in the future).
That is where you can update your card information.