Hopefully, we would be OK with regard to securities law if we premine 100% and distribute those coins to users of our app at no cost.
I think so if you can also get many other apps to use your coins and create a huge diverse ecosystem for these tokens (but I don't think you can do that without losing your focus on your app!), but consult your own attorney. Note smooth and others felt premine was culpable. I argued against that. None of us are lawyers.
I doubt distributing 100% at no cost is a problem.