Mejai's stacks should be shown in the post-game screen
On the rare occasion that someone actually buys Mejai's Soulstealer or Sword of the Occult, I find it interesting to see how many stacks they actually managed to get / keep.

In-game, you can select the champion to take a look. However, the post-game lobby doesn't show the stacks on stacking items, so there's no way to see how many stacks someone ended the game with after it's finished. It would be nice if the stacks were shown there.