I think there may be some misunderstanding here.
The paid Itch.io version does include the full base game. It is essentially the public version of the game with all paid mods included and no Patron Code required.
A subscription is only required if you want access to Early Access or the Dev Build, meaning newer content before it reaches the public/Itch.io release. You do not need to keep a subscription to get the "full game."
The differences between all versions are described here: https://wiki.kunoichi-trainer.ninja/version-differences the Itch.io version is updated together with the public release, while subscribers get new updates earlier.