You can either stash your API key on your computer or include your API key on each command.
Set your active API key
gradient apiKey XXXXXXXXXXXXXXXXXXX
Alternative: Include your API key for each command
gradient experiments run ... --apiKey XXXXXXXXXXXXXXXXXXX
Obtaining an API key
First, sign in to your Paperspace account. On the left of your home console, you should find an 'API' section. There, you'll find a form where you can create API keys. You'll use the API keys you generate here to authenticate your requests.