In order to buy life insurance on another person there must exist insurable interest, meaning you rely on the other person for financial support, or you stand to lose financially if the person dies.
Usually, there is insurable interest between spouses, siblings, parents and their children, relatives, and business partners, among others.
In order to buy life insurance on another person you must have their knowledge and permission. And, you must be a legal adult.
In addition, the person you want to insure may need to answer some health questions, take a physical exam, and sign the application for coverage.
Learn more about What is Insurable Interest?