Good god, I was trying to dig so hard and missed that this method is called automatically, even though I’ve looked through it! 
Thank you so much for pointing me out in right direction!
That solves my question in case I have AIController tasks, but I might have other non AI tasks for my NPCs, for example play some animation (cutscene or, I don’t know, sound). Is there a way to create some method inside my classes, that would be called at certain point the way OnMoveCompleded() is called? (I’m thinking of Tick() again lol)
Thanks again for help!