Yes. All of our icons are available to download for free. If your icons are licensed under Creative Commons Attribution (CC BY) they are free to use, as long as the member properly credits you in their work. We include the proper line of credit in a member's free download to ensure credit is given. If a member doesn't want to give credit, they can pay to use the icon license either through their Pro account or through a single $1.99 purchase.
Any public domain symbol is free to use, even commercially.