WHMCS PayPal Billing Agreements

Features

Automatically charge users the correct invoice amounts, eliminating accidental overpayments or missed/late payments
Only attempts to automatically charge invoices with the payment method as "PayPal Billing Agreements"
Customers can make one-time payments from the client area without being redirected to PayPal and back (after successfully setting up a billing agreement)
Honors the "Process Days Before Due" and "Retry Every Week For" automation setting for when to charge a customer's PayPal account
Honors the "Auto CC Processing" setting for individual customers
Displays whether a customer has an active billing agreement or not in the admin area

Prerequisites

For this addon to work correctly, you must have PayPal reference transactions enabled on your PayPal account. You will need to contact PayPal and request that this feature be enabled for your account. Usually you'll need to go through an approval process, which may include a personal credit pull.

Installation

Rename the directory /templates/six to match the name of your current client area template
Upload all files to your WHMCS root directory
Run the following SQL statement to create the billing agreement table in your WHMCS database:

CREATE TABLE `paypal_billingagreement` (
    `id` varchar(32) NOT NULL,
    `client_id` int(10) NOT NULL,
    `acc_email` varchar(127),
    `acc_payer_id` varchar(17),
    `acc_payer_status` varchar(10),
    `acc_first_name` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci,
    `acc_last_name` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci,
    `acc_business` varchar(127) CHARACTER SET utf8 COLLATE utf8_general_ci,
    `acc_country_code` varchar(2),
    `status` varchar(32) NOT NULL,
    `created_at` int(10) NOT NULL,
    `updated_at` int(10),
    PRIMARY KEY (`id`),
    FOREIGN KEY (`client_id`) REFERENCES `tblclients` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
);

Activate the module in Setup => Payments => Payment Gateways
Enter your PayPal API Username, Password, and Signature in Setup => Payments => Payment Gateways => Manage Existing Gateways => PayPal Billing Agreement
(Optional) Set your IPN URL to https://your.site/modules/gateways/callback/paypalbilling.php. If you don't setup your IPN URL, consider enabling "Enable Cron Status Check" under the payment gateways module options. (Warning: Running the cron status check with many active billing agreements may significantly extend the runtime of the cron job)
Create a custom email template under Setup => Email Templates. Make sure the Email Type is set to Invoice and the Unique Name is PayPal Billing Agreement Payment Failed. You may use the following as a starter template:

<p>Dear {$client_name},</p>
<p>This is a notice that a recent PayPal Billing Agreement payment we attempted on your PayPal account failed.</p>
<p>Invoice Date: {$invoice_date_created}<br />Invoice No: {$invoice_num}<br />Amount: {$invoice_total}<br />Status: {$invoice_status}</p>
<p>You will need to login to our client area to pay the invoice manually at {$invoice_link}</p>
<p>{$signature}</p>

Run a cron job at 11:00 PM every night: 0 23 * * php -q /path/to/whmcs/modules/gateways/paypalbilling/cron.php

Upgrade

If you installed this addon prior to May 29th, 2020, run the following SQL statements to update the database schema.

ALTER TABLE `paypal_billingagreement` ADD COLUMN `acc_country_code` varchar(2) AFTER `client_id`;
ALTER TABLE `paypal_billingagreement` ADD COLUMN `acc_business` varchar(127) CHARACTER SET utf8 COLLATE utf8_general_ci AFTER `client_id`;
ALTER TABLE `paypal_billingagreement` ADD COLUMN `acc_last_name` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci AFTER `client_id`;
ALTER TABLE `paypal_billingagreement` ADD COLUMN `acc_first_name` varchar(64) CHARACTER SET utf8 COLLATE utf8_general_ci AFTER `client_id`;
ALTER TABLE `paypal_billingagreement` ADD COLUMN `acc_payer_status` varchar(10) AFTER `client_id`;
ALTER TABLE `paypal_billingagreement` ADD COLUMN `acc_payer_id` varchar(17) AFTER `client_id`;
ALTER TABLE `paypal_billingagreement` ADD COLUMN `acc_email` varchar(127) AFTER `client_id`;
ALTER TABLE `paypal_billingagreement` ADD COLUMN `updated_at` int(10) AFTER `created_at`;

Limitations