To use my icons in your software, on a web site, in a theme etc. you need my _
  permission first. In some cases I allow my icons to be used for free in _
  freeware software, non commercial web sites, in themes etc. 
Payment will be required to use my icons in commercial software, a commercial _
web site or for any other reason commercially. 
You don’t need permission for personal use on your computer. You only need _
permission to use them on a web site, in software etc

THX

Piekarek