Opening and closing workbooks steals memory

Sub Main()
    Dim info, analyse As Variant
    Dim i, n As Integer
    Beep
    Dim colFiles As Collection, f, wb As Workbook
    
    Application.ScreenUpdating = False
    
    Set colFiles = GetMatches("c:\Users\Documents\Analyseenhed\LIMS_2022\", "*Resultat*.xlsx")
    n = colFiles.Count
    i = 0
    For Each f In colFiles
        Set wb = Workbooks.Open(f.path, UpdateLinks:=False, ReadOnly:=True)
        wb.Close
        WB=nothing
        Debug.Print i & " of " & n & "   " & GetMemory
        i = i + 1
    Next f
    
    
End Sub

Function GetMemory()
    Dim oInstance As Object, colInstances As Object
    Dim totalMem As Single, availMem As Single
 
    Set colInstances = GetObject("winmgmts:").ExecQuery("SELECT * FROM Win32_PhysicalMemory")
    For Each oInstance In colInstances
        totalMem = totalMem + oInstance.Capacity / 1024 / 1024
    Next


    Set colInstances = GetObject("winmgmts:").ExecQuery("SELECT * FROM Win32_OperatingSystem")
    For Each oInstance In colInstances
        availMem = availMem + oInstance.FreePhysicalMemory / 1024
    Next
    
    
    GetMemory = Round(availMem / totalMem * 100, 1)
    Set colInstances = Nothing
    Set oInstance = Nothing
End Function