Hello @Joe-And-Gail1
You should never extend a guests booking until you receive payment.
I believe in the US your guests do gain tenancy rights post 30 days so it's particularly important that you look very carefully when deciding to accept longer term bookings about the legal implications in terms of tenancy rights of doing so.
If the guest is still at the listing then you or your cohost need to go to the property to ensure they leave promptly (bring someone with you so you have a witness).