On this page, you can check license allotment for each of the license types that you have. Additionally, you can click the Add Licenses button to purchase more licenses for your team at any time. If you have any questions regarding license pricing or otherwise, please reach out to firstname.lastname@example.org.
Salesforce Service Account/Domain Wide Enablement
Domain Wide Enablement is a method of ensuring that emails and calendar events will get logged from Google to Salesforce for the users that you as the admin choose. The Salesforce service account will be the SFDC user that "logs" these emails and calendar events to Salesforce, without relying on each users' settings and Google/SFDC connection.