The password life time is set to 180 days by default. If you want to change the life time to unlimited, perform the following command in the REPO database:
ALTER PROFILE DEFAULT LIMIT COMPOSITE_LIMIT UNLIMITED
PASSWORD_LIFE_TIME UNLIMITED
PASSWORD_REUSE_TIME UNLIMITED
PASSWORD_REUSE_MAX UNLIMITED
PASSWORD_VERIFY_FUNCTION NULL
PASSWORD_LOCK_TIME UNLIMITED
PASSWORD_GRACE_TIME UNLIMITED
FAILED_LOGIN_ATTEMPTS UNLIMITED;