Trademarks can last forever if they are renewed on time. Keep in mind you will have to continue using your trademark to keep it in good standing.
In the US, you must renew your trademark every 10 years. In addition, between the 5th and 6th year after the registration date, you must file an “affidavit of use” to keep the registration alive.
In Canada, a trademark has to be renewed every 15 years (the renewal period will be changed to 10 years soon).
In Australia, European Union and the United Kingdom, you have to renew your trademark every 10 years.
To open in a new tab, click: How long are trademarks valid for?