Any Excel workbook can be converted to an add-in. To create a protected add-in file, first load the workbook that will become your add-in. Start the Visual Basic Editor by choosing Macro from the Tools menu, then choosing Visual Basic Editor. At the very top of the Project window, select the bold entry that declares the name of the VBA project that is open.
Choose the Properties option from the Tools menu. This displays the Project Properties dialog box. Make sure the Protection tab is selected, and make sure the ‘Lock Project For Viewing’ checkbox is selected. Enter a password in both fields at the bottom of the dialog box. Click ‘OK’ – the dialog box closes.
Close the Visual Basic Editor and return to the Excel workbook. Choose File > Properties. In the Summary tab, make sure the ‘Title’ field is filled in. What you enter here will appear in the ‘Add-Ins’ dialog box used by Excel. Make sure the ‘Comments’ field is filled in.
What you enter here will appear in the description area of the ‘Add-Ins’ dialog box used by Excel. Click ‘OK’ to close the dialog box. Now choose ‘Save As’. Using the ‘Save As Type’ pull-down list, specify the Microsoft Excel Add-In (*.xla) file type.
Specify a name in the ‘File Name’ field. Click ‘Save’. Your add-in file has been created. Finally, close the workbook you just saved as an add-in.
I didn’t know that Excel workbook can be converted to an add-in. Thanks for tips..