Our Global Team Leader, Serengettispirit, posted the following in the official announcements:
The event will end on Sunday at 12 noon CEST – everything connected to the event will end then including the shop for players to exchange their souls. Please ensure that any shopping you wish to carry out is done by this time. We are unable to carry out any after this period. Also, no new event NPCs will spawn after this time.
The Event Chest keys will be exchanged for normal chest keys after the event has ended. This is the same for any souls that are left over at the end of the event. LinK: http://en.board.bigpoint.com/seafigh...d.php?t=517704
Based on this announcement, we know that you will receive an exchange for the left over souls that you have. Please watch the official announcements to find out what exactly the exchange will be for.