Yes, you can easily “reuse” your ESTA. An ESTA is valid for 2 years from the date of issue or after your passport expires. It is possible to enter the United States with an ESTA as often as you like during the period of validity. However, with an ESTA you can stay in the USA for a maximum of 90 days.
It takes approximately 10-20 minutes to complete an ESTA application and it takes up to 30 minutes on average for your ESTA to be approved. In special cases it can take up to 72 hours.
If your ESTA is refused, you will need to apply for a regular visa at the US embassy in Copenhagen.
Is there a limit to how many times I can use my ESTA?
There are no borders. However, you must adhere to the rules that you can stay in the United States for a maximum of 90 days at a time and of course you are not allowed to work with an ESTA.
If you travel to the US several times you may be asked why you are doing this.
Can I reuse my ESTA if I have a new passport?
If you get a new passport, change your name, your gender or your nationality, you will have to apply for a new travel authorization (ESTA).
You will also need to apply for a new ESTA if your answer to any of the “Eligibility Questions” changes.