Warum du bereits einen weiteren Treath eröffnen musstest verstehe ich nicht.

Sub Speichern()
 
Dim FileName As String
Dim Path As String, Pathu As String
Dim wb As Workbook, ws As Worksheet
Dim Ini As Integer, Nbr As Long
Application.DisplayAlerts = False
Application.ScreenUpdating = False
 
Set wb = ActiveWorkbook
 
'Specify the file paths for each sheet to be saved
Path = "R:\02_PM_ZAM\Tools\Tools_Einkauf\OutOfStock_Ablage\OutOfStock_PG"
Pathu = "R:\02_PM_ZAM\Tools\Tools_Einkauf\OutOfStock_Ablage\OutOfStock_PG"
Jahr = Format(DateSerial(Year(Now()), Month(Now()), 1), "YYYY")

lng = 10
Ini = 1

For Each ws In wb.Sheets
    Set ws = Sheets(Ini)
    FileName = ws.Name
    Path = Path & " " & lng & "\"
        If Dir(Path, vbDirectory) = "" Then
            MkDir Path
        End If
        Path = Path & Jahr & "\"
        If Dir(Path, vbDirectory) = "" Then
            MkDir Path
        End If
    Debug.Print Path
    Path = Path & FileName & ".xlsx"
    ws.Copy
    Debug.Print Path
  With ActiveWorkbook
    .SaveAs FileName:=Path, FileFormat:=xlOpenXMLWorkbook, CreateBackup:=False
    .Close SaveChanges:=False
  End With
    lng = lng + 10
    Path = Pathu
Next
Application.DisplayAlerts = True
Application.ScreenUpdating = True
End Sub