You can edit your billing info anytime, as long as your subscription is active. To do so, log into Agorapulse, click on the profile picture in the bottom left of the screen and click Subscription. This will open a screen where you can access your subscription information, Billing info and invoices.
Here you can add other payment methods, as well as change the default payment method. To edit the address/contact details, click the pencil icon in the top right hand corner. Once your changes are complete, don't forget to hit the Update billing info button when you are done.