Many adult children or adult grandchildren purchase life insurance on their elderly relatives to make sure there is money available to pay for the burial costs of their relatives when the time comes.
Usually, there is an insurable interest between children and their parents and/or grandparents. You must have an insurable interest in the person you want to insure for life insurance.
Insurable interest means you either rely on the person for some means of financial support, or that you would lose financially should the person die.
For example, maybe your grandpa helps support you, or maybe you would be the one paying for his burial and final expenses upon his death.
Here's how to learn more - Can I get life insurance on my grandpa?