Found the below solution on the Web at
https://www.datanumen.com/blogs/prot...nlicensed-use/

Option Explicit
Dim dteExpiry As Date ‘Declare variables
Dim flagLocked As String
Dim strPWD As String
Dim strResult As String

Sub Auto_open()
Sheets("Welcome").Visible = True
Sheets("Main").Visible = xlVeryHidden 'Can't be unhidden by the user
Sheets("Defaults").Visible = xlVeryHidden

dteExpiry = Sheets("Defaults").Range("B1") 'Test for Expiry
strPWD = Sheets("Defaults").Cells(2, 2)
flagLocked = Sheets("Defaults").Cells(3, 2)

If dteExpiry < Now() And flagLocked = "No" Then 'Trial period over
flagLocked = "Yes"
Sheets("Defaults").Cells(3, 2) = flagLocked
ActiveWorkbook.Save 'Ensures that flagLocked is set
MsgBox "The trial period has expired. Please contact xxxx at yyyyy"
ElseIf flagLocked = "Yes" Then
strResult = InputBox("Enter password", "Password", vbOKCancel)
If strResult = strPWD Then
Sheets("Main").Visible = True 'Reveal the "Main" sheet
Sheets("Welcome").Visible = False
Else
MsgBox "The password is wrong. Please contact xxxx at yyyyy"
Exit Sub
End If
Else ‘Within trial period
Sheets("Main").Visible = True
Sheets("Main").Activate
Sheets("Welcome").Visible = False
End If
End Sub

Sub Auto_Close()
Sheets("Welcome").Visible = True
Sheets("Main").Visible = xlVeryHidden
Sheets("Defaults").Visible = xlVeryHidden
ActiveWorkbook.Save
End Sub

Using EXCEL 2010 – with the code in Module 1
The workbook does not close if I enter an incorrect password(lockflag set to Yes).
It just stays open.
What am I doing wrong??