Did you imagine that the author(s) of a book or people who are employees of a publishing house earn a living based on selling books. And you take this book of an illegal download site and spread it around.
This is nothing other as packing one's bags in the supermarket and leaving without paying. There you don't need national laws. Your common sense should tell you that this is not right.
You can use tkinter built-in library or other third party libraries like pyqt or kivy. Note that pyqt isn't free licensed for commercial uses.
"For pyqt you can use this useful book:
Rapid GUI Programming with Python and Qt" written by Mark Summerfield.
Your previous comment was about the legal aspect of this work which I answered it. But your recent comment is in the ethical aspect of this work which I agree with you. So I agree that if it is possible to buy this work regardless of the legal aspect it is better to do so.