Lifetime components are an optional feature. Their single purpose is to offer events called in relation to the saved lifetime of the actor.
They are not necessary by any means to save your game since they only add some useful events.
Why can't I just use BeginPlay?
BeginPlay gets called every time game starts for that actor including when game starts, when you load, when the actor didn't exist...
It's not a good representative of the lifetime of the actor. That is why Lifetime events are called only during the actor's lifetime. It doesn't matter if it was loaded, saved, destroyed, etc. It is kind of more deterministic.
Gets called only first time an actor is created.
- When you start a new game
- When you spawn the actor
- Wont be called when you load any game (Resume will be called instead)
Called when this actor is saved
Called when this actor is loaded. When opening a saved game from any level in any situation
Similar to EndPlay, but gets called when this actor gets destroyed during gameplay or at normal endplay. But wont be called when you load a game and this actor gets destroyed as a consequence.