Hello,
I’m planning to buy a license of avast pro. My questions is:
If by any chance I uninstall avast pro or format my Windows 8, could I download or install avast pro again? What should I take care of?
Just keep your license saved in a safe place and you can re-install as many times as you like.
And there is the option to have the license resend to you:
http://www.avast.com/resend-license-paid.php