License Key Deactivate or not? And if so, how miraculously?

[Resovia]

I would like to reinstall CCleaner PRO, after reinstalling the entire operating system of the computer. Do I have to deactivate my previously entered license key and how? In the tab of this program, entitled "License information", there is no option to deactivate the license key - why is this? So, will there be a problem later or not? I'm worried...

[nukecad]

It isn't a problem,
if you have reinstalled the whole OS then simply install CCleaner Free and register it again.
You can quickly download the installer for CCleaner Free from here (it's slightly quicker to use the Slim installer, 3rd down): https://www.piriform.com/ccleaner/builds

You will notice that where a Pro version says 'Licence information' the Free version says 'Upgrade to Pro'.

So simply re-register CCleaner by using Options>About>Upgrade to Pro to re-enter your license key, then click 'Register'.

If you didn't make a note of your licence key then you can get it again here: https://www.ccleaner.com/support/license-lookup

Note that you can do the same if moving your CCleaner Pro from one machine to a new/diferent one, in that case simply uninstall CCleaner from the old machine before re-registering it on the new one.