My deep fryer has a lid that goes on top of the deep fryer after it cools down to keep the cooking oil protected when storing it.
So after I get done deep frying foods I allow the cooking oil and the deep fryer to cool down for an hour or so and then place the lid onto the deep fryer.
Then the cooking oil lasts for at least 6 months before I need to change the cooking oil.
When the cooking oil gets bad and needs changed I pour it out onto the ground to dispose of it although you can also dispose of the old cooking oil in your trash can by putting it into an old coffee container and throwing it into the trash.
Cooking oil is not harmful to the environment so you can dump it on the ground but also some people use it to make biodiesel as well.
At food establishments they usually sell the old cooking oil to places that recycle it and sometimes turn it into biodiesel as well.