30. Licenc es by owners of copyright .-The owner of the copyright in any existing work o r the prospective owner of the copyright in any future work may grant any interest in the right by licence in 3[writing by him ] or by his duly authorised agent : Provided that in th e case of a licence relating to copyright in any future work, the licence shall take effect only when the work comes into existence. Explanation. -Where a person to whom a licence relating to copyright in any future work is granted under th is section dies b efore the work comes into existence, his legal representatives shall, in the absence of any provision to the contrary in the licence, be entitled to the benefit of the licence.