How to activate PDT and get PDT Identification Token

First of all remember you must have a PayPal premier or business account rather than just a personal account. OK, lets get started:

1. Log into your PayPal account. Click on the "Profile" tab.
2. Then below "Selling Preferences" click on "Website Payment Preferences" link which is highlighted as shown :
3. The Website Payment Preferences page opens.
4. Under Auto Return for Website Payments, click the On radio button.
5. For the Return URL, enter the URL on your site that will receive the transaction ID posted by PayPal after a customer payment. Usually this URL is dynamically generated by the control based on the properties you set, yet you need to provide a URL which works as default for PayPal in case you do not provide any return URL by the PayPal Control.
6. Under Payment Data Transfer, click the On radio button.
7. Click Save.
8. Again, Click Website Payment Preferences in the Seller Preferences column.
9. Scroll down to the Payment Data Transfer section of the page to view your PDT identity token as shown in the following screen-shot.

That's it. PDT is now activated.