Only for new sets, but don't be fooled. If I remember correctly, they have limits on how many icons and illustrations you can download every day. So you actually pay huge amount of money (minimum of $228), for small subset of icons that you managed to download. You can't download entire Streamline set and use it within your library.
Streamline is good, I considered to use it, but it's way way more expensive than any other "Pro" icon pack on the market.