Does a Pokemon have to hold onto an Everstone, even after its evolusion level, to not evolve?

Question

Ok, so let's say I have a Lv. 55 Pupitar that did not evolve because of an Everstone. If the Pupitar levels up, does it have to still hold on to the Everstone, or does it need to keep holding on to the Everstone to prevent from evolving at later levels?

Answer 1

It will still have to hold the everstone. If you miss your evolution level, leveling up normally will make you evolve.

Answer 2

You can make it hold the everstone to make the evolution animation not show up at all. You can also take the everstone away and "astonish the Pokémon so much while evolving with the B button that the evolution stops"