Unless revoked, Your ESTA authorization is generally valid for multiple trips over a period of two years (starting the date that you are approved) or until your passport expires, whichever comes first. This means that as long as you received an ESTA authorization to travel, you do not have to reapply during the validity period.
If your ESTA expires while in the U.S. it will not affect your departure.

Receiving ESTA authorization does not mean you may stay in the U.S. for two years. It only allows you to travel to the U.S. under the terms of the Visa Waiver Program (VWP), which only allows you to stay in the U.S. for 90 days or less. If you plan to stay for longer than 90 days, you must obtain a visa at the nearest U.S. Embassy or Consulate.

In most cases, ESTA applications are processed instantly. However, some applications may require additional processing and can take up to 72 hours.

No, travelers with valid U.S. visas are not required to apply for ESTA. ESTA is only for those traveling under the Visa Waiver Program.

No, ESTA is not a visa. It is a travel authorization that determines the eligibility of travelers to enter the United States under the Visa Waiver Program.

No, once an ESTA application is submitted, it cannot be updated. However, travelers can reapply for ESTA if there are any changes to their circumstances or information.

An ESTA is not a visa. It does not meet the legal or regulatory requirements to serve in lieu of a United States visa when a visa is required under United States law. Individuals who possess a valid visa will still be able to travel to the United States on that visa for the purpose for which it was issued. Individuals traveling on valid visas are not required to apply for an ESTA.