issue after paypal express payment

We are currently having a issue where when a user hits complete checkout after the paypal payment page it gives us the error You do not have permissions to make this api call. system is in live/production all api credentials match that which is on our paypal. and ssl is setup along with the ipn handler going to the right address. not sure what is wrong really need some help.

https://wordpress.org/plugins/paid-memberships-pro/