i've been completely absorbed to this game. not just the ahem scenes is great but the plot is actually interesting. and i do think we need more of Naomi.
Hey Faikony!
The premium version is usually ahead of the free version by 2 versions/updates. It's also a once off payment, giving you access to future premium versions. It's a way to support us and get your hands on the updates a lot sooner.
However, if you're happy tackling the game whenever, I'd stick to free version as the game will always be free, just takes a tad bit longer to see those updates.