The Events database does the trick, but I've only given you a "Helpful" answer because the events database only goes back 3 months and doesn't hold into account recently created VMs. To circumvent that issue you'd need a "last log in"-field.
I realise 3 months is longer than 90 days, but I'd like to get a timestamp of when the last time they logged in was to take back to the end user. If it's been more than 3 months I'll just be able to say "it was more than 3 months". 
This is the query I used:
create table #LocalTempTable(
DesktopID nvarchar(512),
EventText nvarchar(512),
Time datetime)
INSERT INTO #LocalTempTable(DesktopID, EventText, Time)
Select DesktopID, ModuleAndEventText, Time
FROM dbo.VMEevent
order by Time DESC
DELETE FROM #LocalTempTable
WHERE DesktopID IN (
SELECT DesktopID
FROM #LocalTempTable
WHERE EventText like 'User%')
SELECT DISTINCT DesktopID
FROM #LocalTempTable
DROP TABLE #LocalTempTable