If you're 18 years old and your mom owns the car, but you're paying for the insurance, your mom may still have some authority over the car. This is because, as a parent, she has the right to make decisions about her property, including the car, until you turn 18. However, once you turn 18, you are considered a legal adult and are responsible for your own affairs. At this point, your mom no longer has the authority to take away your car keys or make decisions about your car without your consent.
It's important to note that even though your mom may not have the authority to take away your car keys, she may still have the right to make decisions about the car's maintenance, repairs, and insurance, especially if she is the one paying for these expenses. It's important to have a clear understanding of your rights and responsibilities as an adult and to communicate openly with your mom about your expectations and boundaries. If you're unsure about your rights and responsibilities, it may be helpful to consult with a lawyer or a legal professional.