Q. Will I need to apply for an ESTA every time I travel?
An ESTA authorisation is generally valid for two years. This means that as long as you received an ESTA authorisation to travel, you do not have to re-apply for two years, unless you have obtained a new passport in this time. You may update your travel information; however this information is optional and is not required.
You must however, ensure you take a printed copy of the document with you each time you travel as it contains your ESTA number that may be needed for reference purposes.