The message you saw about the cron not running in the last 24 hours refers to the fact that no automation has taken place recently. That means any invoices that should be generated, services that should renew, etc., are not occurring automatically because the cron has not been running.
When you installed Blesta, you should have also created a cron job on your web server and set the cron command to the command shown in Blesta (also shown in Licensecart's screenshot). The server will then run the command at an interval you set (we recommend every 5 minutes), which in turn will run all of the automation tasks under [settings] -> [Company] -> [Automation].