curl --request POST \
  --url https://api.altostrat.io/workspaces/{workspaceId}/billing-accounts/{billingAccountId}/subscriptions \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "product_quantities": {
    "locations": 5,
    "users": 25
  },
  "metadata": {
    "project_id": "proj_abc123"
  }
}'

{
  "id": "sub_a1b2c3d4e5f6g7h8",
  "billing_account_id": "cus_a1b2c3d4e5f6g7h8",
  "status": "active",
  "currency": "usd",
  "product_quantities": {
    "locations": {
      "price_id": "price_123abc",
      "quantity": 10,
      "interval": "month"
    },
    "users": {
      "price_id": "price_456def",
      "quantity": 50,
      "interval": "month"
    }
  },
  "metadata": {
    "order_id": "6735"
  },
  "current_period_start": "2025-10-15T00:00:00Z",
  "current_period_end": "2025-11-15T00:00:00Z",
  "created_at": "2025-10-15T12:30:00Z",
  "updated_at": "2025-10-20T09:00:00Z"
}