To get Clearbit up and running in your Salesforce org, you will need to complete these three steps:
Get Clearbit from the AppExchange and install in production. Configure your settings to make sure all records stay up to date with current data.
All Salesforce users who want to access Clearbit data will need to have a license. Ask your Customer Success Manager how many Clearbit licenses you have available. You can always increase the amount of seats if you need more.