OLD QB-Core

['markedbills'] 				 = {['name'] = 'markedbills', 			  	  	['label'] = 'Marked Money', 			['weight'] = 1000, 		['type'] = 'item', 		['image'] = 'markedbills.png', 			['unique'] = true, 		['useable'] = false, 	['shouldClose'] = true,	   ['combinable'] = nil,   ['description'] = 'Money?'},	

Add the following line to qb-core > server > player.lua anywhere around 87-140 area under metadata

    PlayerData.metadata['cargoxp'] = PlayerData.metadata['cargoxp'] or 0