lets say i make 200 per month from any network or google , they pay me 3 months . then they cancel my account accusing me i spam , or clicked on own ads or some other reason ? then do i have to pay money back that they already paid me .. do they cancel cheques which are in bank and not cashed yet ?
They can cancel any cheque that hasn't cleared, yes. They would have to sue you to recover any money already in your hands.
Until you have the CASH Google can do whatever they want. If I was in your shoes, I would switch to EFT as soon as possible. Then you do not have to wait on checks to clear.