curl --request GET \
  --url https://api.synthra.ai/v1/analytics/usage \
  --header 'Authorization: Bearer synthra_live_abc123def456'

{
  "billingPeriod": {
    "start": "2024-03-01T00:00:00Z",
    "end": "2024-03-31T23:59:59Z"
  },
  "requests": {
    "used": 8473,
    "limit": 100000,
    "percentage": 8.5
  },
  "tokens": {
    "used": 184729,
    "limit": 10000000,
    "percentage": 1.8
  },
  "sessions": {
    "active": 47,
    "limit": 100,
    "percentage": 47.0
  },
  "tier": "pro"
}