This option prevents the tracking script from trying to match the full URL of your landing page when there’s a ‘?’ in the URL with additional data behind it. For example, your landing page might be http://landingpage.com/lp1, but some traffic sources may add additional tracking data to your URL for tracking purposes, causing the URL which they’re redirecting traffic to your landing page with to look something like this instead:
http://landingpage.com/lp1?webm=234&utm=source&a=b&c=d
In the example case above, if you do not enable the “ignore query string” option, the Paykickstart tracking script will attempt to match the entire URL including the added tracking fields as your landing page URL, and since that is not actually your landing page’s URL, it will fail to record that traffic.
Since there are cases where you may not want to “ignore query string”, such as if your landing pages use querystrings in your actual landing page URL, this is a user-configurable option.