Here is the script for generating installed patch report for any computer.
1.Copy below code in notepad and save file as "update.vbs".
Wscript.echo "Script is running..."
Set objSession = CreateObject("Microsoft.Update.Session")
Wscript.echo "ObjectSession created."
Set objSearcher = objSession.CreateUpdateSearcher
Wscript.echo "objSearcher has been set."
Set objResults = objSearcher.Search("Type='Software'")
Wscript.echo "objResults has been set."
Set colUpdates = objResults.Updates
Wscript.echo "colUpdates has been set."
Wscript.echo "Starting loop."
For i = 0 to colUpdates.Count - 1
Wscript.echo ("Number " & i & ": " & colUpdates.Item(i).Title)
2. Now create a batchfile. Type below command in batchfile
cscript update.vbs > report.txt
3. Save both file at same location. and run batch file. A new file report.txt will be created with all installed patches.
Note: "Automatic updates" service should be running to complete the task.