An Unity pro application is not password protected by default. It is possible to create or change a password at any time. The password is case-sensitive and it must have a size from 8 to 16 alphanumeric characters. The password robustness is increased when it contains a mix of upper and lower case, alphabetical, numerical, and special characters.  Procedure for creating the application protection password is a below :-

1. In the project browser right-click Project.
2. Select Properties command from the popup menu.
Result: The Properties of Project window appears.
3. Select Protection tab.
4. In the Application field, click Change password ....
Result: The Modify Password window appears.
5. Enter the new password in the Entry field.
6. Enter the confirmation of the new password in the Confirmation field.
7. Click OK to confirm.
8. Click OK or Apply in the Properties of Project window to confirm all changes. If you click Cancel in the Properties of Project window, all changes are canceled.

Once you download a password protected application into the plc, it can only be accessed with a password. See the below snapshot.




Please note this feature is available from Unity Pro V8 and above.