If you move while it is casting the item will cancel out and then be gone from your inventory. Just had a jax do that in my last game and we were all confused as to what happened. Luckily we were super ahead and it didn't matter, but it could make the difference between an early win and a late loss.
Nautoday2 votesPSA: he lied to you.
It expired after 4 minutes.
If you go into the practice tool and try and use and move instantly, it stops the summoning, but it doesn't remove it from your inventory. After it starts channeling for .5 seconds or so, you can't move anyway and must complete the summoning.
Potato Doc3 votesWent back and checked, it was not in fact after 4 mins had passed
Xikini1 votesRift Herald BUGFIX Fixed a bug where canceling Eye of the Herald's summoning ritual at the very end of its 0.25 second wind-up (before the uncancellable 3-second channel begins) could cause the item to go on an extremely long cooldown, preventing it from being used before it expires
Skins Project1 votesCC cancels it.
Moving does not.
AmazoX1 votesWhaaaaaaaaaaaaaaaaaat.
Doctor Jarvis1 votesThat...seems like a big oversight