§1. When the period for which profession was made has elapsed, a religious who freely petitions and is judged suitable is to be admitted to renewal of profession or to perpetual profession; otherwise, the religious is to depart.
§2. If it seems opportune, however, the competent superior can extend the period of temporary profession according to proper law, but in such a way that the total period in which the member is bound by temporary vows does not exceed nine years.
§3. Perpetual profession can be anticipated for a just cause, but not by more than three months.
Source: Code of Canon Law (Vatican.va)