My grandmother signed a sale agreement with a promoter for a flat/ apartment where she was staying at that time. The property is in Kolkata, West Bengal. She passed away after that. The promoter did not register the sale agreement. The agreement was signed around 2014-15. We are staying at this flat/ apartment since Dec. 2002. How long is the sale agreement valid? Can the promoter throw us out in future? The promoter also has the property deed in his possession. Kindly, answer.