Well Aakash, a tagline is not always required and by that I mean it’s not really necessary to put a tagline but it can sometimes prove to be nice to have one. Its required when you want to do intensive marketing to attract the customers you can use a punch line or a tag line to describe your product in an interesting way.
It has lasting impact on people’s mind its just like advertising, it can help you promote your product in a more fascinating way.