curl --request GET \
  --url https://api.getlago.com/api/v1/activity_logs/{activity_id} \
  --header 'Authorization: Bearer <token>'

{
  "activity_log": {
    "activity_id": "1a901a90-1a90-1a90-1a90-1a901a901a90",
    "activity_type": "billing_metric.created",
    "activity_source": "api",
    "resource_id": "5eb02857-a71e-4ea2-bcf9-57d3a41bc6ba",
    "resource_type": "BillableMetric",
    "organization_id": "1a901a90-1a90-1a90-1a90-1a901a901a90",
    "logged_at": "2025-03-31T12:31:44Z",
    "created_at": "2022-04-29T08:59:51Z",
    "user_email": "dinesh@piedpiper.test",
    "activity_object": {
      "lago_id": "dad68bc7-c01a-4ad8-a87b-13e78693a5bc",
      "plan_id": "b9155544-e261-4e92-b54e-f65d7609294c"
    },
    "activity_object_changes": {
      "plan_id": [
        null,
        "b9155544-e261-4e92-b54e-f65d7609294c"
      ]
    },
    "external_customer_id": "5eb02857-a71e-4ea2-bcf9-57d3a41bc6ba",
    "external_subscription_id": "external_id"
  }
}