The PayPal Website Payments Pro is actually two different services:
1. PayPal Express Checkout, which is a more tightly integrated version of the regular PayPal payment.
2. PayPal Direct Payment, which will let customers pay with a credit card directly on a site without logging into or even having a PayPal account.
To use Direct Payment, PayPal requires that you also use Express Checkout. There are two different gateway modules for Express Checkout and Direct Payment, you must use both to use the Direct Payment method.
PayPal Pro is used through a software development kit (SDK). To use it the server must have PEAR (PHP Extension and Application Repository) installed and available to the hosted sites. It usually comes with php and is installed by default but there can in some cases be some additional configuration required.
To use the PayPal SDK on a Windows server the admin/paypal/Services/PayPal/EWPServices.php and admin/paypal/Services/PayPal/CallerServices.php scripts will need to be edited and all instances of "/tmp" which is a typical Unix/Linux path will need to be replaced to something like "C:temp" or another directory that exists on the server.
The communication with PayPals server is encrypted and requires Curl with OpenSSL. It also requires a certificate that you get from your PayPal account by clicking "Profile", "API Access" (under the section "Account Information"), "Request Certificate" and filling out the form. The file that you get is called cert_key_pem.txt and should be uploaded to the admin/paypal directory in AShop Deluxe. This is also where you get your username and password. The username is what you should enter into the Merchant ID field in the Payment menu in your AShop Administration Panel. The password is what you should enter into the Security Secret field in the Payment menu in your AShop Administration Panel.
There is a test mode but it can only be used with a test certificate and you can only get one of those by registering at PayPals developer central.