curl --request POST \
  --url https://api.mnemom.ai/v1/billing/validate-promo \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "code": "<string>"
}
'

{
  "valid": true,
  "discount_percent": 123,
  "discount_amount_cents": 123,
  "name": "<string>"
}