Well, the level itself is the currency. Which is not obvious at all. I was constantly looking for an indicator of where my money was xD Figured it was just a hidden variable since it wasn’t that important or the game was unfinished or something.
Figured it out though but yeah, I think that is not intuitive.
My suggestion would be a money counter, and that the money “skill” can’t decrease. Also adding a symbol to indicate which cost money would have been useful, but I wouldn’t detract points for that in a jam