Sir i would like to ask what if someone publish game made in unreal engine in market and earn money and doesnt pay any royalities . So how epic game will know who is using their game Engine.? Is there any kind of tracker in engine ?

[atypic]

All licensees under the EULA have a contractual obligation to report revenue and pay royalties. Failing to do so would constitute material breach of the EULA, making the license terminable. And if the license terminates, then use of the engine in the game constitutes copyright infringement, and your game can be removed from all distribution.