On this topic several misunderstanding occurred. I want to resolve them.
The main difference between the free and pro version ist not the offline map. The free version is financed by a advertising banner on buttom of the map.
At the moment this ad does not appear because of wrong settings in the Apple portal. Soon the banner will appear.
There are several discussions on the current implementation of the offline maps (raster / tile images) that should discussed separated from the free and pro version. In future I will support vector maps on base of the filetype .osm. The background of the current implementation is, that there is no free vector map renderer on iOS. This I have to develop by myself or by license a commercial framework. I want to develop it by myself but this is work for several month. Because I want to release L4C this summer and there are also more important thinks to implement in this app, I use the current implementation of offline maps.