If your lease deed exceeds 12 months, then you require a lease agreement registration. If you have not registered your lease agreement, you cannot present it as proof in a law court. Lease agreement registration also helps in protecting the rights of the parties. A landlord is more comfortable giving his house to a renter if the lease agreement is legally and validly registered. A lease agreement need not be registered if it is only for 11 months. This is why you would see a common practice of leasing out properties for only 11 months.