I was trying to implement paypal Recurring just like ARB in authorize.net to charge monthly billing to the user what I found is this and I also found the source code here.
But I am unable to find my my_api_username, my_api_password, my_api_signature as they were required in the api
$API_UserName = urlencode('my_api_username');
$API_Password = urlencode('my_api_password');
$API_Signature = urlencode('my_api_signature');
And I am unable to find them in my account in profile tab, if you have any code sample and anyone can guide me where can I find these variables in my account. I want to implement this for sandbox.