If you simply suspect drug use it may not be enough grounds to evict unless you can get proof. You can serve Form N6 based on illegal acts if you are able to gather evidence about the illegal drug use and/or possession/distribution by your tenant or their guests at the rental unit. However,  if your house contains 3 or fewer residential units, you can serve the Form N7 based on the disturbances. In both cases, you will also need to submit Form L2 and a Certificate of Service when applying to the Landlord and Tenant Board for a hearing. The cost of filing an application with the Board is $201 (in-person filing) and $186 (online through e-File).