Before place in shopkeeper editor gui
After you finish editor and close the GUI, item will remove the expire date and replace by duration lore to let player know the expiration of item.
The lore will be replaced in first line so please be careful to play with it.
You can config the duration lore in lang file.
When player trade complete, item will become timed item.
Expire date will start to count from the time player complete the trade.