While 1e/2e's Enchant An Item spell required Permanency to make magic items retain their enchantments, this is not true in 3e.
Once you have crafted a magic item (using the appropriate Item Creation feat), and spent the correct XP, the magic item is complete and enchanted for as long as the object lasts.
Permanency has also been dropped in power from 1e/2e's 8th LV to 5th LV in 3e. It also now only applies to making spell effects permanent and is not involved in the creation of magic items.