You will need your New Relic API key for authenticating your requests. The New Relic documentation for accessing this can be found here.
You can set the API key as the environment variable
you can pass the API key as an argument in the interface constructor:
from newrelic_api import Applications app = Applications(api_key='4baa5d20cfba466a5e075b02698f455c') response = app.list(filter_name='demo')