I advise you NOT TO PURCHASE any theme from Mageewp.
The ones who did are no longer having support. Apparently the developer left people on their own. I strongly suggest you to adopt another theme from another developer. A sad thing. It used to be a great theme in the past. I even assume it is not even compatible with 7.x.. Don't waste your precious time.
@jbb I am using PHP 7.1 with OneTone ProVersion: 3.2.5 (latest version is 3.5.2.) It's working.
But as Leo mentioned, the support is almost inexistent and releases after 3.3. are all affected by some troubles with a 3rd party extension...