Is my ESTA still valid?

You can have a look at the status of your ESTA any time. You can contact us at any time to check on its status. If it’s been less than 2 years since you applied, and your passport is still valid, then your ESTA should be, too.
Your ESTA authorisation will run out after the two years from the date on which it was authorised, or when your passport expires, depending on which is sooner.
Also, ESTA does not renew itself automatically, irrespective of whether you end up visiting the USA or not at any point during the two year period. When this occurs you will need to apply for a new ESTA yourself, following the same procedures as you did the first time you applied for ESTA via the website as mentioned above.
If you experience a change in legal name, gender, citizenship or other alteration to your biographical information, then you will have to apply for a new ESTA . Other changes can be updated to your application at any time. If, however, your status or any new information about you compromises your eligibility Visa Waiver Program, then you will obviously not be able to apply for ESTA again.
It is important to bear in mind that the validity of your ESTA authorisation is only important for your travelling to the U.S. If your ESTA runs out once you have reached U.S. soil, or afterwards, it isn’t important, and you can leave the U.S. without a problem.