I need a Pay to Regsiter plugin

I need a pay to register plugin that registers wordpress users and not users for the plugin.

I need to allow multiple users with same email adress which I have been able to accomplish via this plugin:
https://coffee2code.com/wp-plugins/allow-multiple-accounts/

But I am using wishlist member for registering users and while it’s a really nice plugin it does not allow multiple users with same email. Does anyone have any suggestions?

Does wp e-commerce members only register wp users or e-commerce users?

Thanks for your help!