In Oregon, the maximum duration of a standard residential lease is one (1) year. Leases can be longer, but it is rare. In Oregon, a lease of any length can be verbal instead of written.
Despite the fact that oral or verbal leases are valid and enforceable, it is highly recommended that all lease agreements be in writing. It is easier to enforce a written lease, and it is easier for either party to prove the terms that they have agreed upon.
If there is no term described in the rental agreement, it is determined to be a month-to-month tenancy (as long as it is not week-to-week) (OR Rev Stat § 90.220 (2017)).
The information for this answer was found on our Oregon Residential Lease Agreement answers.