curl --request GET \
  --url https://provider.api.nadles.com/v0/subscriptions/{subscriptionId}/product/billable-metrics/ \
  --header 'nadles-provider-key: <api-key>'

{
  "data": [
    {
      "name": "<string>",
      "label": "<string>",
      "quotas": [
        {
          "quota": 123,
          "usage": 123,
          "period": {
            "unit": "<string>",
            "value": 123
          },
          "end": "2023-11-07T05:31:56Z"
        }
      ]
    }
  ]
}