Contrary to what you might expect, a problem with the key itself or the ignition are some of the reasons why your keys get stuck. Unless you’ve made it a habit to stick your keys in the mud, it’s very difficult for debris to get in there and clog the works. While it’s unlikely – small pieces of metal can stick to a key if you just make one, for example – it’s highly unlikely.
The most common cause of stuck keys is simply installing inappropriate traffic. When you park your car and go to remove your keys, your car must be set up in a very special way to be removed. In particular, the gear selector must be in park and the steering wheel must be in neutral. If you are still in the car or the wheel is cut too far to one side, the ignition will not release your keys as a safety feature.
It is also possible that your ignition is not turned off. Remember, when you turn one of your keys, it turns on your car’s lights and radio. You have to turn off the ignition all the way – the extras – to release the keys.