Relax because once you get through this ESTA USA application, you’re good to go for two years. You will be able to make as many trips as you like. You do know, however, that there is a 90 day rule, right? You want to know that of course because a trip longer than 90 days requires a visa. If you need a visa instead, you will want to move forward with that application.
If you need an ESTA, there is no visit to the consulate or US embassy. You just simply have to fill out an electronic application for travel authorization to the US. The ESTA process approves you for the visa waiver program. That means you get to essentially skip all the hassle and just get yourself ready to travel.
Are you going to be traveling to the US really soon? Are you already making plans? The reason I ask is because you are supposed to fill out this electronic application ahead of time. There isn’t a large window of time required, but you are supposed to give the authorities 72 hours notice prior to traveling.
If you are trying to buy cheaper airline tickets ahead of time, then you don’t want to wait until 72 hours ahead of your trip to apply for your ESTA USA authorization. What you could do then is apply with ESTA and the VWP much earlier. That way you would have everything taken care of already.
Think about when you want to travel to the US. Start with your ESTA application so that you are good to go. Then you can start booking your flight, hotel and everything else that you need to take care of in terms of travel arrangements. And remember, your ESTA will be good for two years, unless your passport expires first.