Amberdata offers three different subscriptions plans to choose from when it comes down to API usage.
Connections / Subscriptions
Free (no longer available / legacy)
Accounts, Transactions, Tokens & Market Data across top exchanges.
On Demand (no longer available / legacy)
Full historical on-chain and market data, metrics and signals.
2 connections / 10 subscriptions
Order Books, Derivatives Markets, Custom Metrics, SLA and more.
See https://amberdata.io/pricing for more details on each plan.