The "lifetime" business (although the more common phrase is "useful life") is no longer the default language.
Of course, you cannot undo past naming agreements. But nowadays, "term limits" are very common. We adopted them at NC State around 2010. However, as I work with clients to develop new naming policies, I am aware that many institutions still refer to "lifetime."
And I should add that at NC State, we still used "useful life" if the donor insisted. For many institutions, a "transitional period" before shifting to strictly term-based naming is common. Here's a portion of the naming policy I wrote for a university last month:
"The attached Naming Agreement must be used in all cases. It will specify whether the naming is for the facility's useful life, subject to this policy, or "temporary." The University encourages temporary or term namings in most cases, with the term generally not exceeding 10 years. Shorter terms, but not less than five years, may be considered based on the facility or object's expected useful life. The determination of whether a naming is permanent or temporary will be made in consultation with the Dean of the affected College and the Naming Committee."
The corresponding naming agreement for my client included the following language, borrowing liberally from what we used at NC State, and included:
"Subject to the other provisions of this Agreement, the Facility shall be named XYZ for a period not to exceed 10 years, which is the term of years approved for this Agreement in accordance with University policy."
"Upon expiration of the period designated above, the exclusive right to determine the Facility's name shall vest in XYZ University. Among other options, XYZ University may change the Facility's name or remove the current name from the Facility. XYZ University may also offer the current naming donor the option to make a contribution of the stated new naming rights value or to elect to retain the Facility's name indefinitely after the designated period expires."
Does this help?