If a proper payment gateway is configured in the portal general settings then you'll be able to accept payments from practically any module from your crm, you just need to have a numeric field from which retrieve the payment amount.

In this tab you'll be able to set the following options:

• Enable Payment: with this option, you can enable/disable the "Pay Now" button visible on the top of each record.
• Payment Amount Field: here you must set which field will be used for each record to retrieve the payment amount, any numeric field can be used.
• Payment Currency Field: You can set here the module field to specify the used currency for each record, if set to default then the general portal currency will be used.

With this feature you can update your record values when a payment is processed from the portal, for example, you can choose to automatically change some payment status picklist or update any other value when your customer complete a payment.

You can set as many fields you need and you have two possible cases after a payment is processed, the cases are On Success Payment and on Cancel Payment.