Voltage's games are mostly paid games, meaning if you buy a character's route, you can view them anytime time you want; the prologue and 1st episode are free and if you want to continue reading the story then you can purchase it (there are stories that for a certain time they can be viewed for free). With free games, like Shall We Date?, you have to buy tickets and special items in order to proceed with the route. The game Liar! is considered a free game, but it doesn't offer those annoying avatars like in Shall We Date?, it's pretty basic.
Thank you so much. Just to confirm one last time, if I buy Ivan's route I won't have to pay anything after that
If you purchase Ivan's main story, then the payment is complete and you do not have continue purchasing the main story.
However, if you want to play Ivan's other stories (sequel, royal wedding and sub stories) you must purchase them. Hope that helps!
Thank you :)