Not to erect a building on the land unless the plans and specifications thereof have been approved in wrting by the transferor or its appointed agent and such approval shall not be unreasonably whiheld PROVIDED HOWEVER that approval to such plans and specifications shall be deemed to have been given in respect of any building which has been erected and occupied for a period of twelve months or more PROVIDED FURTHER that this clause shall cease to have effect after the expiration of five years from the date of registration of the plan.