Enable the lock mode in order to freeze the attendance after a certain set duration. When enabled, editing or marking after the allowed date can only be done by a privileged user or admin.

 Step 1:  Menu > Academics > Attendance > Attendance Settings

Step 2: Select 'Lock' and select the lock duration as shown in the above figure. After the Lock duration, the attendance will be automatically locked.

Step 3: Click on 'Save' to save the settings

After the settings, you will get two options as 'Submit' and 'Save' in the Attendance register page as shown below,

Save - Save the attendance using this option. You can edit the attendance after entering.

Submit - If you click on Submit, the attendance will be submitted and locked.