You should certainly write your own essays, since you need to express your personality, and it would be unethical if you didn't! But if English isn't your first language, if you're not confident about your writing skills, or if you just don't know where to start, it could make sense to have a professional help you. You need to come up with the ideas, and write a first draft. Then, the professional can help with the flow, the grammar and the writing style. He or she could also tell you if you are missing anything important. But the content behind the essay really needs to come from you.
You're hiring the professional to be your coach and editor, not to write the essays for you.
You should certainly write your own essays, since you need to express your personality, and it would be unethical if you didn't! But if English isn't your first language, if you're not confident about your writing skills, or if you just don't know where to start, it could make sense to have a professional help you. You need to come up with the ideas, and write a first draft. Then, the professional can help with the flow, the grammar and the writing style. He or she could also tell you if you are missing anything important. But the content behind the essay really needs to come from you.
You're hiring the professional to be your coach and editor, not to write the essays for you.