I got my roll from studio and my last frame had a certain black spot in the left upper corner.Any idea what it can be ? The rest of them were fine.
You will need to inspect the negative to see if the spot appears there also. If not, it is some artifact of printing/scanning, the problem is fixable, and you should ask the lab to redo it.
If yes, it could be a number of things. I'll hazard a guess: given the blurry edges, it's an out-of-focus insect that happened to sit on the lens / fly by when you took the photo. But it could also be a development error, for example an air bubble that prevented the developing solution from reaching that area in the negative properly.
By the way, I'd be more worried about the slight vertical banding seen in the image. Unless this is a processing/scanning artifact, it could indicate that something is wrong with your camera's shutter.
I once was shooting outside with multiple camera bodies. After setting one down to use another, I picked the one on the ground back up and began to use it again. Glancing at the rear LCD screen I noticed a really bad dust goober on an image I had just taken. I checked the frames immediately previous and saw the same thing. The odd thing was that the dust spot was moving around the frame from shot to shot. "Ok," I thought, "The air from the mirror movement is blowing this really large dust ball around a bit."
I was preparing to remove the lens and do an 'emergency' field cleaning of my sensor by using a blower bulb, which is something I avoid doing unless absolutely necessary, when I noticed the half completed spider's web spanning the front of the lens hood. Then I found the spider who was weaving it. That's pretty much what your example looks like. Dust on the front of a lens usually isn't visible in image because it's so small and so out of focus. But an insect that is much larger than a grain of dust, even though it is extremely defocused, can show up as a very blurry spot.