to get Internet Security or not?

i have been using avast free for a while. recently i deleted it and reinstalled. Its now telling me I have 5 days left to register. It also shows an offer for Internet Security for $34.95. Im trying to work out if I should upgrade to Security or stick with the free version.

I am currently using avast v8.0.1482 on Windows 7 on a laptop. i am thinking of upgrading my laptop in the near future and was wondering if the licence can be used to reinstall on any new computer, or if i would need to pay again if i do upgrade the computer. I was also wondering if it was a once off charge or if its a yearly one.

Thanks in advance.

if the licence can be used to reinstall on any new computer
the license file is valid for the amount of computer and time you buy it fore....also if you reinstall