ac unit in window keeps turning off?

It could be a low pressure switch shutting off the unit. Or a temperature sensing bulb. See if the coils are freezing up when it's running. If they are, you could have a leak, bad compressor or the filter just might be dirty.

If you're having to use an electrical reset to start it back up, it could be high head pressure. See if there's any damage to the copper lines (kinks) and if there's damage to the fins, try to straighten them out. It could also be a build up of dirt on the condenser coil or fan(s) or something outside that's preventing the unit from giving up the heat it absorbed in the room (ex. another building close by, bushes, etc)

The question has long been settled. Turning it off saves money. The more your place heats up because it is off the more money you will be saving. I'll gather some links to back this up. It is a myth that it will take more to cool it back down than leaving it on. Your landlady is wrong to enter your room but right in that it saves energy. Who is paying the electric bill? "In the summer, you can follow the same strategy with central air conditioning, too, by keeping your house warmer than normal when you are away, and lowering the thermostat setting to 78°F (26°C) only when you are at home and need cooling. Although thermostats can be adjusted manually, programmable thermostats will avoid any discomfort by returning temperatures to normal as you wake or return home." Although they are speaking of furnaces and heat, the same principles apply here "A common misconception associated with thermostats is that a furnace works harder than normal to warm the space back to a comfortable temperature after the thermostat has been set back, resulting in little or no savings. This misconception has been dispelled by years of research and numerous studies. The fuel required to reheat a building to a comfortable temperature is roughly equal to the fuel saved as the building drops to the lower temperature. You save fuel between the time that the temperature stabilizes at the lower level and the next time heat is needed. So, the longer your house remains at the lower temperature, the more energy you save."

The safety you refer to is a built in GFCI . Its quite common for then to fail, or become defective, and not illegal, or unsafe to remove them and install a standard 240 vac cord end. I have converted a number of them for a particular nursing home that uses "Islandaire" thru the wall heat/cool units. This will void the manufacturers warranty though !

take it out of the window and remove cover and clean your condensing coil but i would have to say your compressor is going bad time for a new one

my guess would be the AC unit is defective, since you say that the unit's reset is tripping, not your house's circuit breaker.

see if its on power saving mode and make sure filter is clean