If you want to create your own applications that use your consumption data, you need a personal access token to do so.
You can create a personal access token in your Account settings. Click your name or email in the top main menu, and then select Account settings. On a mobile device, Account settings is found by tapping the top right menu button.
In the Account menu, click Access token. If you already have a personal token, it will be shown here. Otherwise, click Create access token to create one.
Please read the API documentation for more information on how to make requests to the API using your personal access token.