I had read in the past a challenge which consisted in transforming the windows’ notepad into a shareware. I have no idea if this has already been done, and as I have always been excited by Reverse Engineering, I have always wanted to write an essay about it. I hope that you will also have fun in reading it as I had in writing it :o) This essay is written in 2 parts. Part 1 deals with a transformation which needs no GUI (interface), only pure coding under an hexeditor. Part 2 will deal with GUI and has the typical registration box with name and serial calculation.