The National Lottery has been exempted from the new measure.
He and wife Chris, from Largs in North Ayrshire, claimed the prize in 2011.
Didzis Pirags used the £6.50 he had left in his National Lottery account to play the online game.
The tradition event, known as El Gordo, is held on December 22 each year.
National Lottery operator Camelot has revealed that the winning ticket in this month's unclaimed EuroMillions draw was purchased in Dorset.
Tuesday’s winning EuroMillions numbers are 18, 31, 32, 38, 48, with Lucky Stars 04 and 12.
Ahead of the latest big winner's reveal, we look at what happened to some past winners.
The prize will be paid out at a ticket validation appointment before the winner decides whether to go public.
For 25 years the National Lottery has been changing lives by creating thousands of millionaires.
UK ticket-holder makes history with huge windfall after matching five main numbers and two lucky stars.