User account created without completing payment

Please i have this issue while using the plugin;
I use paystack as my payment gateway. When people try to sign up and choose a membership plan, they get directed to the checkout page where they would normally fill in their details. When they’re done and click “pay with paystack” it redirects to paystack payment environment where they would put their card details for example. Now this is the problem, even without completing their payment, an account is created for them! If they go back to the previous page they’ll discover that they already have an account created, even without finishing payment. Please how do we make it such a way that they don’t have accounts created till they have actually paid and transaction is completed.