LedgerSync has two price lists: one for the LedgerSync app and one for the LedgerSync API. There's no double billing. If you sign up for the API, LedgerSync links your LedgerSync account to the API and you get both. The API is an extension of the LedgerSync software.
The API is meant for larger, enterprise-style firms. For a small firm, for example one with 5 clients, the API is more than it needs, and the LedgerSync app on its own is the better fit.
Email support@ledgersync.com, use the chat in LedgerSync, or book a demo at calendly.com/ledgersyncdemo.