Should I be honest about my past history of attending a Master degree in the past? I am planning to attend a PhD program in the future. Should I be honest that I have some experience of attending a full-time Master degree in the past for three years? I had a somewhat rocky relationship with the thesis supervisor resulting in me being kicked out from the program. I am a bit worried that revealing this might be not too beneficial for me during the application process. Can I pretend that I did something else during the three years? In reality, I did some work in a part-time manner while attending my old program (self-employed).
Consider the worst case scenario under each action: telling them and not telling them. 

Under the first it might be a bit harder to get accepted and your search might take longer. You have more to explain about how you will be a success.

Under the second, you are found out and expelled and blacklisted for dishonesty. Academia is a kind of a small place in each discipline. 

The best scenario for both is about the same.