The MPL library uses adaptive payment. Adaptive payment allows sellers to use your Paypal merchant (business account) to pay customers. Thus, if the seller has only a personal PayPal account, he can use your application using adaptive payment, he will be able to pay the buyer’s PayPal account. You can send money to one or more recipients.
You will learn more about adaptive payment from here: http://youtu.be/GjEPcf7fvkM
To make your MPL library live, you need a Live Paypal account. If you do not have it, create it here: https://www.paypal.com/us/webapps/mpp/merchant
Then go to My Account> Profile> My Sales Tools Click Online Sales> API Access> Refresh to display the API Access page. If the update parameter is missing, you will see the create parameter. You will get this information in the youtube video above. Below is a document to make your application live: https://developer.paypal.com/docs/classic/lifecycle/goingLive/
Then go to apps.paypal.com, and then log in using your current PayPal credentials, and then create the app there. You must enter a description and stream for your application. Once they confirm this, you will receive a "Live Application ID". You must use it in your MPL to make it alive.
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