For reference, see this post and thread: https://forums.frontier.co.uk/showthread.php?t=148965
TL;DR
If you buy ED on Steam, or use the Steam Key that FD Provides to you for free to activate the game on Steam, EVERY PURCHASE you make from now on, EVEN ON THE FD Store means that 30% of the purchase goes to steam. This includes anything that is available on steam. Buy a Paintjob on the FD store? 30% goes to steam.
The only exception is physical merchandise that is NOT available on steam such as Mugs, Hoodies, Shirts, Books, or such.
This is not properly understood by people, and is often mentioned as "Oh that can't be right". Well, it is true.