In order to get life insurance on someone else, you must have an "Insurable Interest" in the person you want to insure.
This means you either rely on the person for some form of financial support, or that you would suffer some financial loss or cost should that person die.
Usually, Insurable Interest exists between spouses, parents and their children, business partners, life partner, or some relatives.
Learn more about who you can insure for life insurance.