Yep, if you want Pro you'll need to buy again

There have been heaps of changes since 4.8!! You can check out the changelog here, to see what's been going on
Lime Wire » Features History

Why not download the free basic version first, see if you like it & once you're happy with everything...then think about Pro. Just remember that if you don't have the 4.8 installer saved, you'll lose that version if you install a newer version of LW.