Unable to register Avast 6

Have not received registration key having been through following process twice:
Starting point - “licence about to expire” or similar.
Clicking on link in pop-up opens web page with ad for full version. Clicking on free version link takes you to Cnet; downloaded installer from there.
Used installer to uninstall previous version; re-boot; install Avast 6, all ok.
Advised to register or protection will expire in 30 days.
Pop-up window over UI invites purchase of full version or option of registering free version.
Clicking on register free version brings up registration form requesting name and email.
Entered details, result: pop-up, “retrieving information - please wait”.
Then a window saying: “Thank you for registering free version / Try Internet Security 20 day free trial”. No other option except to download and no license key has appeared in more than 24 hours.
Clicking on download link of Int. Security trial stars an update in the UI which finishes in seconds with “already up-to-date” and “last encountered error - the license is invalid or has expired”.
Registering online got me a key by email which is for Avast 4 or 5 and doesn’t fit the fields in the registration form of Avast 6.
Far from giving me 30 days to register, Avast has disabled itself and left me unprotected within 24 hours of being installed. Twice.
Any ideas, anybody, of what’s going on here?
Have now installed AVG to provide some protection and feeling less than impressed from the colossal waste of time when the process should be quick and simple.

I think you are confusing several things.

There is the Free edition, and there are trial versions. The trial editions for Avast Pro or for Avast Internet Security will expire and the registration for those editions needs payment.

If you want the Free edition of Avast, then download the Free edition and register (for free).

Once you installed and register the Free edition, you may receive some promotion, if you want to upgrade to some edition other than the Free one.

I think you first installed some of the trials, and then when you finally registered the Free edition you confused the ad / promotion / offer too.

Now you would need to remove the other security tool you installed (choose the correct removal utility from http://thewebatom.net/uninstallers/security-software/) and run it under Windows Safe Mode.

Then download the Free edition of Avast (not the trial), install it, reboot immediately, test it, update it, configure it… during several days.

After 30 days using thee Free edition (not trial), you still need to register (for free), and you can use the built in method ( Avast main GUI → maintenance → registration) or the more traditional method from http://www.avast.com/en-us/registration-free-antivirus.php.

Sometimes, reinstalling avast over a previous installation could be “considered” as piracy by itself. So, you can have your expiration time reduced. But, now it’s difficult to say as you’ve uninstalled avast.
I suppose you’re running one antivirus at a time…

Many thanks ady4um and Tech for you prompt and helpful rsponses. I didn’t download any trial versions but I did try to upgrade to Avast 6 without having fully removed the running version. Probably. Initially tried to run “setup_av_free_cnet.exe”, it failed, then used the uninstall option contained within this installer. Seemed to work, re-booted, install seemed to work this time but registration not possible. I guess this is where Tech’s point about piracy applies if the previous version had not been fully uninstalled.
Following your suggestions, uninstalled AVG, ran Avast uninstall utility in Safe Mode to remove any possibly troublesome remnants, re-booted and installed Avast 6 and this time registation worked OK. So thanks for the help.
Now feel much more disposed to hand over a little cash for extra protection.

Congratulations! And welcome!