Frostolo I think you can add a web storage.
Check to see if local key exist. The local key would be the Var you create for the coins) Name: coins Text Display: COINS
In Layout Add webstorage.
EVENT = webstorage
ACTION= System - set value (Choose your var "coins) - int(WebStorage.LocalValue("coins"))
I think that's correct. If not I'm sorry it's been a while....