The National Lottery is urging people in the Bournemouth, Christchurch and Poole area to check their tickets.
A £1 million EuroMillions prize from the November 4, 2025 draw remains unclaimed.
The winning Millionaire Maker code is HPCF58869, and the deadline to claim is midnight on May 3, 2026.
Local winner Jamie Heavens has joined efforts to find the ticket-holder, describing how his own win changed his life.
Officials say if the prize is not claimed in time, the money will go towards National Lottery-funded projects across the UK.
