Whenever Yesware makes a call or communicates with your Salesforce organization, we will use API calls. This would include actions such as using the Salesforce sidebar to look up Accounts/Leads or syncing Yesware tracked emails into Salesforce. Depending on the type of action, there might be several API calls made.
If you only want certain events in your Salesforce org, your account manager can request to not have open events, clicked link events, etc synced into Salesforce.
In addition, your Salesforce Admin can check the API call usage in Salesforce and if needed, request a limit increase with Salesforce.