In order to buy life insurance on another person you need an Insurable Interest in that person.
This means, you either rely on that person for some means of financial support, or that you would suffer some financial cost or financial loss if that person dies.
So, insurable interest may exist between spouses, siblings, parents and their children, and business partners, and among others.
That means, an adult child may purchase life insurance on his or her parent or grandparent, for example.
Here's how to get an end of life insurance plan on someone else.