I'm tracking the lead generation form conversions using Google Analytics and using Google Ads to drive paid traffic to the website. I'm using Drupal 7 as CMS for the website.
Most of the inorganic visitors who come from GAds, bounce back without completing the form. Let's say, Visitor 'A' visits the website by clicking Google Ads and bounces back without completing the form. After a day or so Visitor 'A' comes back to the website 'directly', and then completes the form. How to automate this tracking and find that the visitors' main source was Google Ads even though he later comes back directly by typing the website's address?