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

{
  "object": "list",
  "data": [
    {
      "id": "bm_w9x0y1z2a3b4c5d6",
      "object": "billableMetric",
      "aggregation": "SUM",
      "createdAt": "2024-01-15T10:30:00Z",
      "description": "Total tokens consumed by Claude language model interactions",
      "merchantId": "org_e7f8g9h0i1j2k3l4",
      "mode": "usage",
      "name": "Claude Tokens",
      "productId": "prod_m5n6o7p8q9r0s1t2",
      "unit": "tokens",
      "updatedAt": "2024-01-15T10:30:00Z"
    },
    {
      "id": "bm_a1b2c3d4e5f6g7h8",
      "object": "billableMetric",
      "aggregation": "SUM",
      "createdAt": "2024-02-01T14:45:30Z",
      "description": "Gigabytes of cloud storage utilized",
      "merchantId": "org_e7f8g9h0i1j2k3l4",
      "mode": "usage",
      "name": "Storage Capacity",
      "productId": "prod_m5n6o7p8q9r0s1t2",
      "unit": "GB",
      "updatedAt": "2024-02-15T09:20:00Z"
    }
  ],
  "pagination": {
    "limit": 10,
    "offset": 0,
    "total": 2
  }
}