I just bought a Pro CCleaner, I can install in 3 pc, but how do I install it in another computer? Please help!
If you have bought the 'Professional Bundle' then it can be installed on 3 PCs.
Simply download CCleaner and install it on the other computers(s) which will give the Free version.
You can download from here:
https://www.piriform.com/ccleaner/builds
Then go to Options>About and click on 'Upgrade to Pro'.
In the box that comes up enter your licence key and click on 'Register'.