It generally doesn't need to be checked like your engine oil. I ALWAYS check them in the fall when the boat is being put away. There's 2 plugs, a drain and a top level. In the fall, just the lower is pulled, and only long enough to see if the oil is good, milky colored, or water.....
If milky or water, and it's being stored in an area that freezes, it's going to need immediate attention to prevent potential freeze damage and/or rusted bearings.
It's a good time to pull your prop and inspect the shaft at the same time, to see if fishing line is wound up on it. If so, there's a good chance it will damage a seal, allowing water into the case.
Owner's manuals are downloadable, free of charge. Likely a good plan to do that and familiarize yourself. There's a good chance being familiar with it can save you down time and expensive repairs.
