[Mento]

Well you need two things to destroy and make it respawn in 5 minutes:

pawn Code:

SetTimerEx("PickupRespawn", 300000, false);

and

pawn Code:

DestroyPickup(pickupone);

So something like this:

pawn Code:

forward PickupRespawn;

public OnPlayerPickUpPickup(playerid, pickupid)
{
    if(pickupid == pickupone)
    {
        DestroyPickup(pickupone);
        SendClientMessage(playerid, COLOR_WHITE, "You picked me up!");
        SetTimerEx("PickupRespawn", 300000, false);
        return 1;
    }
    return 1;
}

public PickupRespawn()
{
    pickupone = CreatePickup(1318, 23, 0, 0, 0, 0);
    return 1;
}