That doesn't look like a Sign API key — they start with abnd_sign_.
Each key includes a monthly call allowance by plan: Starter 10,000 · Professional 100,000 · Business 1,000,000. Every API response reports the live state in its RateLimit headers.
Starting bundles for the common integration shapes. Pick one when creating a key, then adjust individual scopes as needed. The key always stores the expanded scope list.