Your invoice may say Paypal Subscriptions - that is the payment choice. If you have not reconnected your paypal subscription to sales@merchantmoms.com, it still needs to be done.
Go to https://merchantmoms.com/billing/clientarea.php
choose My Invoices
Click on the invoice you need to pay using the view invoice link
If Paypal Subscriptions isn't in the drop down box, choose it, then choose the Paypal button
