Symantec Backup Exec 2012 Agent Licensing

You would require 3 Agent for Windows for Servers 1, 2 & 3. (Application agent licenses are not required as BE has an agent for MS SQL, but not for MySQL & Sage SQL)

And you would require 2 Agent for Applications & Database licenses for Servers 4 & 5

Lastly, if you are planning to use another server as the Backup Exec media server, then you would require the Backup Exec core (server) license as well.

However, if you plan to use any of servers 1, 2 or 3 as the BE media server, then you would require the Backup Exec server license and 2 Agent for Windows.

And if you plan to use servers 4 or 5 as the BE media server, then the license requirements would be same as mentioned first ( 3 Agent for Windows, 2 Agent for Applications & DBs & 1 Backup Exec server license)