This license does not include the right to re-sell or compile assets from illustratious to replicate a similar or competing service.
For personal use
You can use any of the assets (i.e. illustrations, line art and printables) free of cost in any of your project. You do not need to ask permission but you are required to give credit to illustratious.
If you can not give credit to illustratious you are required to buy commercial license.
For commercial use
You are required to buy a commercial license to use any of the assets (i.e. illustrations and line art) in your commercial project.
1 commercial license covers 1 asset for 1 project.