Talk:Kha'Zix/@comment-25337957-20150218004600/@comment-4636093-20150218020727

The evolutions are permanent. You get to evolve one of them at levels 6, 11 and 16, so you end up with 3 evolved skills and one unevolved under normal circumstances.

(However there is also an easter egg when you're in game with an enemy Rengar, if you both hit over level 16 then you get assigned a quest to kill the other, if you win then you get a 4th evolution point and can evolve all your skills.)