It is very likely that you have a lease. In Oregon, commercial leases are not enforceable unless their value is less than $1,000 for the whole agreement, or they are in writing. (ORS 72A.2010).
If you cannot find your lease, think back to how you and the property owner agreed that you would rent your space. Did you go back and forth through email? If so, search your emails. If you used a software program to sign, like Docusign, you may be able to follow the link to your signed lease in that program, or you may have a copy in your email or on your computer. If you used the services of a broker or an attorney, reach out to them for a copy. If you are in a complex with other tenants who likely have the same or similar lease, you could ask to see theirs. If you have a good relationship with the property owner or property manager, you may simply contact them for a copy. If you are not on good terms with the property owner and have no other way to obtain a copy, make sure the lease provided is consistent with your recollection.
If you had a lease and the terms have expired, you are now considered a “hold-over,” or month-to-month tenant. This means that you would owe the property owner at least 30-days’ notice of termination. ORS 91.070. You can negotiate the lease and payment terms if you want to stay in your space. Do not forget to get it in writing.
If you do not have a written lease and only an oral agreement, then you may not have an enforceable lease. Do not just walk away, though! If you leave without paying, the property owner may still have some rights because you were in possession of and benefiting from the property. Check with an attorney to understand your rights and obligations. If you want to stay, negotiate a written lease with the property owner as soon as possible.