There are limitations based on age and tax year. Credits may apply on state tax returns as well. You can't predict whether you will need nursing home, assisted living or home-care services. Medicare covers all costs for skilled care for 20 days after a hospital stay. After 100 days, Medicare pays nothing.
Some financial planners recommend long-term care insurance.
Also, policies often are full of disclaimers, so you might not get what you need even after paying premiums for years. People often put off this decision because they feel fine now. However, there is no guarantee on your health. If you are unsure about purchasing insurance, do a trial application. If you are rejected, it will not go on your permanent health record.