GET /v1/usage returns what the Usage page shows, using the same API key you send requests with, so a script, a status bar or a coding tool can check what's left without signing in to the dashboard.
curl https://api.openadapter.in/v1/usage -H "Authorization: Bearer sk-cv-..."
You get your plan, how much of each limit (5 hours, day, week, month) you've used and how much remains as a percentage, when each one resets, and your requests and tokens over the last 24 hours. If the key has its own request or token cap, you also get what's left on that key. Every key can read it; it only ever shows your own account.