Backup fails instantly with the error 'This License key is invalid for this edition of SQL Server (Instance (local))' when trying to do SQL Database Backup.
With SQL Plugin 5.0 you must license the plugin for the specific edition of SQL you are running (i.e. You have SQL Enterprise and you have a SQL Standard plugin license key, or vise versa).
Other possibilities are:
You are running a Trial Version of SQL (plugin does not work)
You have upgraded to SQL 2005 from an older version of SQL
Article showing how to find the version of SQL you have:
If you need to know NetVault Supported Editions of SQL then refer to KB Article:
Regardless of the reason you need to contact your Quest Sales Rep, or Keys (https://support.quest.com/LicenseKey.aspx) to resolve the issue.
BakBone SFDC Solution Number: 00003469