LineIcons Free
You can – use, edit, and distribute with your personal/commercial projects, except reselling or redistributing as ‘Icon Pack’ from any other sources.
1. Commercial/Personal Use – Allowed.
2. Redistribution with Projects – Allowed.
3. Attribution – Required.
4. Reselling or Redistributing Source Files as ‘Icon Pack/Icon Font/Icons’ from Other Sources or Public/Private Domain – NOT Allowed
LineIcons PRO
You can – use, edit, and embed on your personal/commercial project, except reselling or redistributing.
1. Commercial/Personal Use – Allowed.
2. Embedding on projects and pass along to non-creators – Allowed.
3. Attribution – Not Required.
4. Reselling or Redistributing Source Files – NOT Allowed.
You can detailed comparison between Free and PRO version from here
As LineIcons free version is licensed under CreativeCommons you can learn more from here
Clarifications:
Brand Icons: The brand logos and social media icons are used in LineIcons project, trademarks owned by the respective entities. Use them by following their brand guidelines.