I edited a document by mistake, Pages 13 did not ask me if I wanted to save the document before closing.

Even though im completely disappointed by all new apple products such as iWork, Mavericks, iOS 7, iPhone, etc... I decided to give it a try and use Pages 13 instead of Microsoft Word for Mac to start working on my Thesis Project, I did not know i was making such a big mistake. I was doing some adjustments to my work and my colleague closed Pages, what surprised me was the fact that Pages 13 did not ask me if I wanted to save the changes before closing, because of that I thought the changes were not made to the document just like Pages '09 but when I opened it again to continue with the Thesis I was really surprised that all the changes and information the Thesis had were completely gone. If Pages 13 its not going to ask me if I want to save the changes, at least I expect that those changes do not happen to my document.

So my question is, how can I prevent this to happen again in the near future?

( Sorry for my misspealling and grammar, this is my third lenguage.)