Software Licensing for Excel Add-In Check License on Startup

ThisWorkbook

Private Sub Workbook_Open()
    httpRequestCheck
    With ThisWorkbook.Worksheets("Sheet1").Range("A1")
        ' the And .Cells(4, 1) = 0 is probably redundant, and if you are allowing more than one activation per license key you should remove that part.
        If .Cells(3, 1).Value = "valid" And .Cells(4, 1) = 0 And .Cells(5, 1) <> "in_use" Then
            'call your add-in here
        Else
            'if the license is not valid, the number of activations remaining is greater than 0, and it is not in use elsewhere we should display the license activation UserForm.
            Activate_License
        End If
    End With
End Sub