Thats good to know thanks!
Actually you can use the app store after the beginning of the game, anytime you want, how to do it is however a bit more tricky.
Viewing post in Feedback (Demo & Public Versions)
Nah its planned to be more obscure. Also in the full game i do plan of adding a quest that makes the app store work anywhere, just not planned for the demo.
Spoiler:
It should be able to be used again when doing an alterante ending where you can move around freely in the starting town. But i think i maybe have disabled the menu there so I need to ckeck out if it still works.