An Agreement is entered into between the parties upon the agreed terms and conditions and hence, the life of any agreement of validity of an agreement is also subject to the discretion of the parties free consent. Whatever may be the nature of the transaction??? sale, mortgage or license agreement....the life of the Agreement is upto the discretion of the parties.
Under a sale transaction, when a property to sold to a party and when the title is transfered absolutely, then that party has perpetual right to that property.
The term of any kind of agreement can be perpetual, or limited like 1 year/2years/ or any other limited period. It depends upon the will of the parties.