Creation Club

Creation Club is a feature which was added to Fallout 4 in patch 1.10.

Overview
Creation Club is a collection of all-new content for Fallout 4 as well as The Elder Scrolls V: Skyrim. It features new items, abilities, and gameplay created by Bethesda Game Studios and outside development partners including community creators. Creation Club content is fully curated and compatible with the main game and official add-ons, meaning using Creation Club content won't disable achievements.

Credits
Credits are the currency used to buy Creation Club products. and can be bought on Xbox Live, PlayStation Network and the Steam store. On Xbox and Steam, credits can be used on both Fallout 4 and Skyrim Creation Club, but on PlayStation the games' Creation Club uses different credits per game due to technical limitations.

Creating a Creation Club account on Xbox One and Steam will earn you 100 credits to use in Fallout 4 and Skyrim, whereas PlayStation 4 users get 100 credits when logging into Creation Club for each game.