curl --request GET \
  --url https://api.paygentic.io/v0/billableMetrics/{id}/meter \
  --header 'Authorization: Bearer <token>'

{
  "object": "meter",
  "billableMetricId": "bm_abc",
  "totalValue": 42.5,
  "windowedValues": [
    {
      "windowStart": "2025-06-15T10:00:00.000Z",
      "windowEnd": "2025-06-15T11:00:00.000Z",
      "value": 12
    }
  ],
  "groupedValues": [
    {
      "groupBy": {
        "model": "gpt-4"
      },
      "value": 30
    }
  ]
}