If there is no lease and no verbal agreement (agreement is a key term! you have a say too) that's been agreed to for another full year legally you are on a month-to-month based lease. You are not obligated to stay there for another full 12 months. Leases do not automatically renew unless there is a term in the written lease agreement that says it auto-renews.
A lease is a time period contract agreement. When that time period expires there is no longer an agreement.
Month-to-Month stuff is different than a longer term lease. For example you don't have to give or be given as long as a notice to move out and things like that. Month to month leases are much easier on both parties (landlord and tenant).
A thought to consider here though is that you said the written lease expired in 2017. That was 2 years ago. You've been staying there, still, for 2 more years? Then something must be going right, and you get along with the landlord...I'm guessing.
So it may not be a good thing to make a stink about it as long as they're not being unreasonable or causing you grief, etc.
Don't ruin a good thing, if it's going well.
Both you and the landlord are still protected by landlord / tenant laws even if there is no lease. The month-to-month laws are still there, they're just a bit different.