Thank you for contacting us.
> "Will the latter be upgraded every time there is a new major version for free ?"
Yes. The App Store version of Folx (Folx GO/GO+) can be upgraded for free in the tab Updates in App Store app when we release new major versions.
The version of Folx that we distribute through our website is being upgraded according to our Upgrade Policy. Thus, all minor upgrades within a major version (5.0, 5.1, 5.2) will be free for you and all further major upgrades (5.X - 6.X) can be purchased with a 50% discount.
Our Upgrade Policy is listed here: http://wiki.eltima.com/policies/upgrade-policy.html
Also, please note that Folx GO/GO+ from the App Store and Folx PRO from our site are different products with different sets of features and different prices. For more information about the difference between these versions, please follow the next link: http://wiki.eltima.com/knowledge-base/folx-editions.html
> "Is it possible to have multiple version of Folx on the App Store ?"
Unfortunately, this question is not quite clear for us. Could you please let us know what versions of Folx you would like to have in the App Store and why?