There is an easy way to gather Last Logon information from Active Directory System Discovery and the attribute flag for Last logon.

When enabling this attribute the Last Logon timestamp is collected in the inventory.
By then creating some SQL querys and reports can this be viewed.

In this example it joins to Server objects and Missing Agents.

All objects:
SELECT     Name0 AS ‘Computer’, CONVERT(varchar(10), DATEADD(ms, lastLogon0 / CAST(10000 AS bigint) % 86400000, DATEADD(day,                       lastLogon0 / CAST(864000000000 AS bigint) – 109207, 0)), 111) AS ‘Last AD Logon’, Client0 as Client, Operating_System_Name_and0 as OS FROM         v_R_System WHERE     (lastLogon0 IS NOT NULL) AND (Client0 IS NULL) AND Operating_System_Name_and0 like ‘%Server%’ AND  lastLogon0 > 0 ORDER BY ‘OS’
Objects not logged on for 90 days:
SELECT * FROM (  SELECT  Name0 AS ‘Computer’,  lastLogon0,  CONVERT(varchar(10), DATEADD(ms, lastLogon0 / CAST(10000 AS bigint) % 86400000, DATEADD(day,   lastLogon0 / CAST(864000000000 AS bigint) – 109207, 0)), 111) AS [Last AD Logon],    Client0 as Client,  Operating_System_Name_and0 as OS  FROM         v_R_System  WHERE     (lastLogon0 IS NOT NULL) AND (Client0 IS NULL) AND Operating_System_Name_and0 like ‘%Server%’  AND lastLogon0 > 0 ) sub WHERE DATEDIFF(day, [Last AD Logon], GETDATE()) < 90 ORDER BY ‘OS’

Attribute setting: