When people suggest something like that, I want to ask "how old are you?" :D
I'm only just starting to picture the process of "chipping in," plus all the accompanying hassle, and my hand already reaches for my face.
Added after 2 minutes
One-time payment is a more interesting option. Like, you buy the game on Steam and play it. But in the long run, it's less profitable for the developer (probably).
Well, who knows, for example, I most likely won't buy a subscription, but I would buy it as a one-time purchase.
Added after 13 minutes
But ideally, the question here is how to attract players who aren't from HeroesWorld