Users with a role of "admin" or "agent" are considered in-house and there for always submit properties for free. To charge a third party make sure their user role is set to "subscriber".
Charge subscribers per-listing or for any of your membership packages (see below for more details). You can also choose beween one-time and recurring subscriptions.
Supported payment methods are PayPal and Stripe. Payment settings are located under "Appearance > Theme Options > Property Submit".
When submitting a property the user is informed upfront via a notification about the payment terms. After submitting a property, payment methods are provided.
The screenshot on the left shopws how an unpaid listings looks like, when a user visits his/her "My Properties" page.
On the right you can see two example packages we have created for this demo. If you login as "demo" user and try to publish a property you will see the remaining quota for the purchased packaged yourself.
A click on the "Subscribe" button leads you to the package detail page, where you can read more about the package and proceed to make a payment.