Often term policies have a limited duration... 10, 20, 30 years. Some are guaranteed renewable without underwriting.
It is a complex decision and it depends on your situation and possibly the other assets you own. You might want to discuss it with an estate planner. Someone recommended that Ed Slott book on IRA and estate taxes in another post. You should take a look at it.
You should consider the benefit of keeping it before you make a decision.
Especially if you have some sort of lock-in on premium costs. The reason is to mitigate the risk of some sort of unexpected expense (e.g. health) that may deplete your assets before you die and leave you spouse in the poor house. Plus, if your spouse dies before you, you can have your children as secondary beneficiaries on the policy. Assuming you have an estate worth more than $1mm when the final survivor passes... it can help pay taxes. This could be especially important if the assets are in tax deferred accounts and they have to be cashed out because of estate taxes.
You might not be able to buy it today if you went through underwriting and had to have a physical exam by a doctor.
You may find that the same coverage would cost you double or triple if you purchased it today. It might be a good value. You could get a comparative quote to see what a similar policy would cost you today.... Here are a couple of instant quote sites
http://www.term4sale.com/ https://www.nylaarp.com/enroll/product_enroll1.asp
Assume that you might die by 80 years old... that $900 a year invested for 20 years (compounded) will probably not yield $250k (even after factoring in inflation). Take that same scenario to 85 yo.
Another consideration: Say you would like to leave something to your children. Compare leaving that $900/yr invested and compounded over 20 years to the face amount on that policy. Look at the $900 as an investment to help your kids down the road when you pass on.