Pathfinder's Create Demiplane can be cast to increase the demiplane's size, or to add/remove traits.
You can use this spell to expand a demiplane you created with create lesser demiplane (you do not need to create an entirely new plane using this spell), in which case it has a duration of 1 day/level. Alternatively, when cast within your demiplane, you may add (or remove) one of the following features to your demiplane with each casting of the spell, in which case it has an instantaneous duration.
And it requires permanency:
You can make this spell permanent with the permanency spell, at a cost of 20,000 gp. If you have cast create demiplane multiple times to enlarge the demiplane, each casting's area requires its own permanency spell.
But requiring permanency on an instantaneous effect is rather strange, because next turn there is no effect to make permanent, it is already gone.
I'm rather new to PF, so do I need to pay the permanency for the traits version of the spell, or just for the increasing in size?