To Vima reports that private pleasure yachts over 7 m arriving at Greek ports must file a transit log with customs to navigate freely, now online through the myAADE portal. AADE's TEPAI brochure says TEPAI must be paid before a transit log is issued.
How long it lasts
For yachts owned by EU or other residents with all duties settled, the log is valid indefinitely. For non-EU-flag yachts owned outside the EU, or EU-flag yachts owned by non-EU residents, validity is limited while customs and tax duties are unpaid.
What a buyer checks
The transit log and whether it's in date, the TEPAI receipts, and evidence that duties are settled. See buying a boat in Greece.