curl --request POST \
  --url https://api.machines.cash/user/v1/subscriptions/promo/validate \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'idempotency-key: <idempotency-key>' \
  --data '{}'

{
  "ok": true,
  "data": {},
  "summary": "success"
}