There are numerous obvious examples that are exposed to non-lawyers. Lifetime has legal force in everyday contracts and agreements in addition to the "lifetime guarantee" that upstanding organizations such as Sears/Craftsman uphold.
Trusts can be created that have a term that expires a stated number of years after the life of one or more named individuals, and can benefit an individual during their lifetime, with a trust remainder interest going to someone else.
A life estate in property, typically created via a will (to a spouse for example, with the children becoming owners of the remainder interest in the land), or created by a simple deed, allows a person to live on and use the property during that person's lifetime, but not sell the property, because they do not hold the land in fee simple (fee simple meaning they have a full interest in the land).
Life insurance is a contract describing payments relating to a lifetime, and annuity contracts are the inverse contract, payments during the lifetime to the beneficiary / owner.
These are common and everyday uses of contractual English that mean "lifetime".
