How long does patent, trademark or copyright protection last?

A U.S. utility patent, explained above, is generally granted for 20 years from the date the patent application is filed; however, periodic fees are required to maintain the enforceability of the patent.  
A design patent is generally granted protection for 14 years measured from the date the design patent is granted.

A U.S. trademark generally lasts as long as the trademark is used in commerce and defended against infringement.

Copyright protection is for a limited term. For works created after January 1, 1978, copyrights last for 70 years after the death of the author. For works "made for hire" (covering the usual type of work owned by a small business), the copyright lasts for a term of 95 years from the year of its first publication or a term of 120 years from the year of its creation, whichever expires first. For more detailed explanation of copyright terms, visit the Copyright Office webpage or consult this guide on Duration of Copyright provided by the Copyright Office.

trade secret can be protected indefinitely as long as the secret is commercially valuable, its value derives from the fact that it is secret, and the owner take reasonable precautions to maintain its secrecy.