We’ve specially crafted a simple hook (valid for WHMCS 6 or 7) for you to upload to add a link to our client area page, where your clients can view, manage, create or cancel their Billing Agreement with you. This page is at yoursite.com/whmcs/paypalbilling.php
Simply upload the attached insertpaypalmenu.zip file below to your includes/hooks folder in your WHMCS install. You can edit the file contents to place the menu item in the place you desire.