How do we make sure that they pay before registration is complete.

3. How do we make sure that they pay before registration is complete.

Hello mhn1,

Please be noted that if you have a payment question in your form, the users will anyway need to make the payment before the input data is captured successfully.

Example PayPal payment question: If user input the data in form fields and submit the form, they will be redirected to the PayPal payment page. If they do not settle the payment, the submission is treated as incomplete payment and will not appear in your form's submission grid. They will be visible in the "Incomplete Payment" section. The following guides should help you:

http://www.jotform.com/help/564-how-to-view-incomplete-payments-of-your-payment-forms/ 

http://www.jotform.com/help/272-Paypal-Incomplete-Payments-FAQ 

Hope this answers your query.

Do get back to us if you have any questions.

Thank you!