GameStudio : How to remove object after delay

When you pick an item in the inventory and drop it to obj_item_ground, this item is send to the ground. That's fine. I want to add a delay to this item to destroy it, but if I drop 2 items to the ground, only the last is destroy.
Question : How can I create one timer by item dropped ?

Step :
obj_inventory : on Create event

 instance_create(0, 0, obj_item_ground);

obj_item_ground : on Create event

initialTime = 5;
time = 5;
ground = -1;

on Alarm[0] event; if timer is less than 0, object is destroy.

if (time > 0) {
    time -= 1;
    alarm[0] = 30;
} else {
    with (ground) {
        instance_destroy();
    }
}

on Left Pressed event :

if (mouseItem != -1) {
    scr_item_ground_timer();
}

mouseItem is item I drag to the obj_item_ground.

scr_item_ground_timer() :

Here I create the instance of object dropped to the ground and start the alarm[0] timer.

scr_inventory_item_drop(mouseItem);

for (i = 0; i < mouseQuantity; i++) {
 ground = instance_create(obj_player.x + random_range(-30, 4), obj_player.y + random_range(-12, 0), mouseItem);
}
alarm[0] = 30;
mouseItem = -1;

scr_inventory_item_drop is just to clear the array which contains the object dropped.