evergreen

adjective LAW

UK /ˈevəɡriːn/ US

used to describe a legal agreement that will automatically renew (= start again) unless one of the people or businesses involved officially ends it:

evergreen clause/provision/agreement An important goal for every agent is an “evergreen” clause which provides for continuing commissions after an agreement ends.

Evergreen letters of credit may be rolled over indefinitely until the issuing bank provides a written notice of its final expiration.

(Definition of evergreen from the Cambridge Business English Dictionary © Cambridge University Press)