How long is a Canada eTA valid for?

When your eTA application is approved, it will remain valid for five years, or until your passport expires. Be aware that if any of your circumstances change, this could render your eTA invalid. If you apply for a new passport then you will also need to apply for a new eTA as your existing eTA is only linked to your previous passport. You can check the status of your eTA at any time to ensure that it is still valid before you attempt to travel.
During the five years that your eTA is valid, you can make mulitple trips to Canada for business and pleasure purposes. This is the case as long as your trip is not any longer than six months in duration, as any trips longer than six months will require a different visa. The eTA is intended for short term visits only.