A baseline snapshot will not be deleted in the normal IDERA SQL Secure grooming process.

To mark a snapshot as a baseline you can use any of the following paths (both available in the Explorer Permissions view):

• Expand the SQL Server instance of your Audited SQL Servers tree, right-click the respective snapshot, and choose Mark as Baseline
• Click the respective SQL Server of your Audited SQL Servers tree. The Audit History section of the Server Summary lists all available snapshots (you can see here if any of them are marked as baseline or not). Right-click the selected snapshot and choose Mark As Baseline. 

When you select a Snapshot with the option Mark as Baseline, a Baseline Snapshot window opens where you can enter a comment associated with the selected baseline. Click OK to continue.