your move has triggered a conditional move

Hi, I was hoping someone might explain something for me. I was playing a IM rated over 500 points above me. I played well, somehow hung in for many moves. Increasingly throughout the game I would get a message. Your move has triggered a conditional move - and then the computer would make my opponents move for him and I would go again. What is the purpose of this? Is it to give a lesser player like me a chance against an IM? Like a handicap system. Who sets the conditions from which such events arise? Chess.com or the person I was playing? I've never come across it before and was hoping somebody might be able to explain the purpose of such a mechanism. Thank you kindly mrmicawber

It is basically a premove, but it only occurs if you make a specific move. Your opponent can try and predict your move (or use multiple separate possible moves) to auto-move if you make the predicted move. It prevents you from forgetting a plan, not moving, and saves time.

Anyone can do it.

Thanks guys. That's very helpful. 

No problem.

I dont have that option. Do I need a payd membership for that?

No. But you will only see when it is not your move in a game. Also, basic members are limited to one conditional line.

Thanks!

Um, I have done as man as five lines, and I could have made more. And I have never had a premium account.

same as me i dont have premium but i have more than 1 move

It's possible that multiple lines was added to basic members but hadn't been the case before.

oh ok