An offer may come to an end by failure of the offeree to accept within the time stipulated for acceptance by the offeror, of if no such time is stipulated, by failure to accept within a reasonable time.
What is a reasonable time depends on the facts of each case .
An offer may also come to an end by the death of the offeree before acceptance, but the death of the offeror will only result in the lapse of the offer if the performance of the contract depends upon the personality of the offeror. If it does not, the estate of the offeror will be bound if the offeree accepts the offer without knowledge of the death of the offeror.
A counter offer or rejection of the offer also terminates the offer
Revocation of Offer. Offer may be revoked at any time before acceptance, but revocation is not effective unit! it is brought to the notice of the offeree, either by the offeror himself or by a third party whom the offeree believes be relaible