Proehl: How long does a patent last?; Sioux Fall Business Journal via argusleader.com, April 18, 2017

Jeffrey Proehl, Sioux Fall Business Journal via argusleader.com; 

Proehl: How long does a patent last?

"The tenth and last question in the series of questions regarding patents is: How long does a patent last?

The term of a utility patent begins the day the patent is issued and has the potential to last for 20 years from the earliest filing date accorded to the patent application that became the patent. In order for the patent to remain in effect for the entire potential term, the patent owner must periodically pay a maintenance fee to the U.S. Patent and Trademark Office (USPTO). Payment of three maintenance fees is typically required for the full 20-year term."

What Is a Patent Cliff?; Fool.com via Fox Business, 7/6/16

Motley Fool Staff, Fool.com via Fox Business; What Is a Patent Cliff? :

"When a company is issued a patent, it can sell the item covered by the patent on the open market without having to worry about competitors coming in and snatching up a piece of the action. But the problem with patents is that they only have a limited life, and when they run out, they can significantly impact a company's bottom line. This is a particular problem in the pharmaceutical industry, where drug companies rely on patents to sell the products they work so hard to develop. That's why drug companies are often subjected to what's known as a patent cliff.

A patent cliff is what happens when a company's revenue starts plunging, or falling off a cliff, because an established product's patent reaches its expiration date and competitors can then start selling that product. While the term technically applies to any industry, it most frequently comes into play when talking about pharmaceutical companies."