Darren Smith, of Irlam Square, Salford, pleaded guilty to one count of robbery at Preston Crown Court and will be sentenced in the new year.
The charge relates to an armed robbery at the former Leonard Dews jeweller’ s in Lytham’s Clifton Street in September 2011.
It was the third time the store had been raided in four years and witnesses spoke at the time of their shock at the robbery carried out in broad daylight.
Detectives later went on national TV appealing for information over the raid.
The store closed last year before being rebranded as a less exclusive jewellers called Chique.
But that shop was forced to close earlier this year.
The jewellery shop has since been re placed by a homeware boutique called Hidden Gem.
Smith is due to be sentened at Burnley Crown Court on January 10.