In the US it is called being a holdover tenant. If you are paying your rent and you dont leave then the landlord will have to get a court order before he can have you evicted. This will normally take 3-4 months. He cant just kick you out. Do you have a lease for the property?If you still have time on your lease left the lease would transfer with the new sale. In order to ask you to leave early normally a landlord would "buy you out" so to say.

Im in commercial real estate and I deal with holdover tenants all the time. I wouldnt leave unless you have somewhere else to go to first.

You probably have a little longer than a month before settlement anyway if the couple is financing. Residential appraisals and inspections take a good bit of time these days. Most that we do here are 60 day settle (for residential, commercial is much longer).

Good luck. Let me know if you need help translating your lease or anything like that.