Using developer account to test a paid app

I have created an app and embedded the google licensing library to it.The app will be a paid app and I want to test its licensing using test responses from google developer server.

My confusion is :

   (1) Could I use my developer account to test my app?

   (2) Do I have to pay for the app while downloading it on my mobile device for testing using developer account?

Anyone here worked with the paid apps please guide me, seeking for help...