Q: does someone not on a lease require to be given 30 day notice to vacate, when residing in residence less than 90 days?

A: No offense, but nothing in your posting indicates that you have done anything that is legally enforceable against your non-paying tenant. You need to serve her a lawfully worded, lawfully served 72 hour notice to pay the rent owed or to get out. If she does neither within that specified 72 hours (or more if you wish to give her more time), then you must file to evict her in the local court. Do understand that landlord-tenant law in Oregon is highly technical and the landlord must comply with every law and procedure exactly right or risk having the lawsuit thrown out of court, his having to pay the tenant's court costs and attorney's fees (which can be in the thousands, depending), start over from the beginning, all while the tenant continues to reside there without paying anything and feeling now emboldened. So you may wish to review everything with a local landlord-tenant attorney and get their help to maximize your chances of getting everything right the first try - it can save you money in the end, not to mention it helps get rid of the tenant as soon as possible. Also understand that until she either voluntarily vacates or the Sheriff removes her pursuant to a court order, you cannot treat her any differently - no changing locks; no cutting off her utilities; no banning her from the kitchen; etc. If you do, you may be liable to her for several months rent plus her court costs and attorneys fees. You can get rid of her but you have to do it absolutely right or it can get very expensive very quickly for you. Good luck.