Partnership release deed

An agreement in the form of partnership release has been prepared.In the deed only two partners is there and agreed to release after receiving his share. But the agreement has been made as that his share shall be given within 6 months ,If any of the principles inthis deed has been violated.It become invalid. But the Released partner after receiving the money with in 8 months.He claimed that the agreement is void ,because his payment was not paid with in six months. The Early deed was unregistered and this deed was prepared in 200/-Rs stamp paper and unregistered. Also on this basis their GST Registration is being cancelled and continuing the business by the existing partner in the style of proprietry. What are the effects in this?