This Plan is also called "Limited Pay Plan" , you may exercise either of the following options when the plan is paid off after 20 years:
You pay only for 20 years and you are covered rest of your life for free
If you don’t want to keep insurance, you can have the all your money back sitting in “Cash Value”
If you need some emergency funds after 20 Years, you may have a loan against " Cash Value" and pay the interest and principal amount can be adjusted with company at the time of death claim.
Other than this, you may also convert your existing plans to money back plans , if your existing plan permits.