A lapse causes a policy, right, or privilege to end because the person or institution that would benefit fails to live up to its terms or meet its conditions.
For example, if you have a subscription right to buy additional shares of a stock at a price below the public offering price, you must generally act before a certain date. If that date passes, your right is said to lapse.
Similarly, if you have a life insurance policy that requires you to pay annual premiums, the policy will lapse if you fail to pay the premiums in time.