By completing Contract tasks and getting chests, you earn a unique currency – crypto chips. Collected crypto chips can be spent on buying special chests in the store in the "Black Market" section.

Please note that crypto chips are updated with each new season of Contracts. You can spend crypto chips you earned during a specific season while the Contracts are active and for some time after they are closed, and then they will disappear. You can check how much time is left in the store near the in-game currency counters.