A trademark registration can last indefinitely. However, there are a few requirements to maintain the registration. One requirement is that you continue to use the mark in commerce. The other main requirement is that you continue to renew the registration. If you do those things, and assuming your mark does not become genericized, your trademark registration can last indefinitely.
In fact, the oldest trademark registration in the United States dates back to 1884 and is owned by Samson Rope Technologies, Inc. Samson’s trademark is a combination of a design element and the word SAMSON. The registration covers the company’s “cords, lines, and ropes” products. You can see the trademark below.
Because Samson Rope Technologies has continued using its mark in commerce and continued renewing its registration, its registration is over 135 years old. It will be interesting to see how long this registration will last.
More information on renewals
You must renew your trademark registration between the 5th and 6th years after registration, another 5-6 years after that, and then every 10 years after that for as long as you use the mark. For each renewal, you must show the United States Patent and Trademark Office (USPTO) that you are continuing to use your mark in commerce. If you fail to file your renewal documents, your registration will go abandoned.