The icons come in three types of licenses: Free, Standard, and Extended. The free license is attached to the freebies. The standard license is the default one for all premium icons. The extended license is a rare gem and can be requested, well… upon request.
A brief overview of the differences between each license.
Free
Standard
Extended
Can I use the icons for commercial use?
Yes
Yes
Yes
Can I remix, transform or modify the icon?
Yes
Yes
Yes
Can I resell the icons as part of a product for sale?
No
No
Yes
Can I use an icon as part of a logo or other trademark?
No
No
No
Do I have to credit the author?
Yes
No
No
Is there a limit to the number of icons I can use?
No
No
No
Have many users can use the icons?
Unlimited
Depends
Unlimited
That‘s pretty much it. If something is unclear, dive into the documents below.