Just found another great exploit.
1st, find a piece of gear that boosts memory. Then, after adding a new ability to the bar, unequip the memory item and you will still have access to the ability that you no longer have enough memory for!
This allows you to get 1 extra memory slot. After that it will properly start pushing abilities out.
You can trade the piece around to have every one of your party members get the benefit.
On my skill panel I see "Memory slots used: 7/6"
This is better for full party playthroughs as the temporary gear sharing gets 4x the effect.
Update: Seems to only work for 1 extra memory slot. Extras past the first with this technique will push one of your skills out.
That does not work for me. I have 8 slots with 16 memory, if I unequip the amulet with +1, one of my skills turns grey, because he does not count as memorized anymore. He may be still in the list of memorized skills but will not usable.