TN admission is granted for a defined period and can be extended or renewed while the employment and the qualification continue to meet the requirements. It is a temporary category tied to a specific employer and role, and each renewal is examined on its own facts.
Plan renewals around the licence and the job, not the calendar
Hypothetical example: the nurse plans a five-year stay and assumes renewals are automatic. They are not. Each extension or new admission is assessed against the same requirements as the first: citizenship, a listed profession, the qualification for it, prearranged employment with a U.S.
employer and the temporary nature of the stay. A licence that lapses, a role that drifts into administration, or an employer that quietly reclassifies the nurse as a contractor can each end eligibility even though nothing about the person changed. Keep the licence renewal dates, the employer letter and the admission record in one place, and revisit them together well before expiry.
If the household's intentions become permanent, that is a different conversation with different evidence, and it should be raised deliberately rather than discovered at a renewal.