ESTA - How to know/check if still valid?

[shogan1977]

I am travelling to US twice in December - I registered on ESTA either late last year or early this year (can't remember)... is there a way I can check if my ESTA registration remains valid without having to re-register and pay fee?

I am of nationality that is part of visa waiver programme.

[ExXB]

You can check on the ESTA website here. Even if you don't have your application number, you can retrieve it from the same page.

[jackieofalltrades]

The ESTA is valid for two years from the date of it's approval unless your passport expires sooner, where it thus expires on the same date as your passport.