Paying again for a deleted Mac app that was deleted by accident

I paid for the Syncfolders Pro app and also upgraded to the + version. Strangely enough, they show up as two icons on the Mac. I thought I could delete the originally bought one and deleted the first one (Syncfolders Pro). Now I cannot use the Program since the icon for the + version says it needs the other one. I contacted the company and they told me I should look in the Purchased Apps tab and re-download - Since there is no search function (Hallo Apple! How can that be?) I looked through all Apps but could not find it. However, I found my Appstore bill in my e-mails. So, how can that be and how can I get the App back without having to pay again?

Thank you!