Warbonds are a form of currency available in Battlefield 1 that is used to purchase weapons and gadgets in a manner similar to Battlefield Hardline. Warbonds are obtained from simply leveling up in multiplayer, with levels dictating the amount awarded. Upon purchasing all available content, Warbonds will stop being awarded.
If a player purchases any shortcut kits, he will still be rewarded with War Bonds when promoted. Any additional Warbonds above those needed to purchase remaining unlocks will be useless.