is a website created with nice page fully autonomous?

I just started the trial version and am quite satisfied with its features.
I understand that any HTML code created would use CSS style sheets and maybe other files that are hosted on a server.
I would like to know if these style files can be hosted on our own server or would our website be required to access them from a nicepage server. This would mean that we would be bound to maintain a subscription to nicepage as long as we use the website created with this system.
We have something similar for another website and don't like it at all because it has several bugs that we cannot repair as we do not have access to that server.