Life insurance companies require their be an insurable interest between the person who owns the life insurance and the person who's life is being insured by the life insurance policy.
That means that, if the insured person passed away, it would suffer financially.
For example, you could take out life insurance on someone to whom you loaned a large amount of money, so that you would get your money back if that person died. Or, someone who you would pay for their burial, such as, your parent or spouse.
Usually, insurable interest exists between spouses, parents and their children, siblings, relatives, and business partners, etc.
Life insurance companies look at immediate family relationships as an emotional loss when death occurs, which justifies financial remuneration.
However, even taking out a life insurance policy on a relative will have some financial considerations in determining how much life insurance you can place on them.
Here's is an article that explains in more detail Who can you insure for life insurance? - to help you better understand how insurable interest works, and who you may insure.