By default, when you close the program, it minimizes itself to the System Tray (Notifications area).

What does it do in the background?

If you minimize the program window while it is performing a scan or repairing the errors, the operation will continue uninterrupted.

If not, it would simply remain minimized for quick access later and will not consume any system resources. Just like you would minimize a typical window.

You can also safely exit the program if you do not intend to use it at that point in time.

How to access the program again:

Locate the Registry Reviver icon in your System Tray, right-click on it and select Open Window

How to exit the program completely:

Locate the Registry Reviver icon in your System Tray, right-click on it and select Exit