If the Design is NOT UP FOR SALE,
You know how the meme goes.
IF the Design IS:
1- Sold designs may be freely utilized by the buyer in commercial and non-commercial work.
2- Sold designs can be midly edited (read: a few small detail changes such as mild color changes, or eye color changes.). Art Styles do NOT count as design changes.
2b- Character name, sexuality/gender can be changed to the buyer's preference.
3- Sold designs may NOT be gifted or resold unless specified in the design's page. You're buying a character, not a lamp.