No problem.
Didn't notice you asked something else till today, the answer is rather simple, i can't access source right now, so i'll post an example:
if (player.getInventory().getItemById(1234) != null)
player.setAccessLvl(1);
PS: This is merely an example, without checking source, methods should exist, at least, almost like that, don't forget you also need to check count and delete the item from player's inventory (not sure if you need this).
If you need more help let me know.