Not sure whether adding this post will be of help, but still...
Could it be that, rather than the license expiry notification, Carlmikael is perhaps wishing to refer to the upgrade one (reads "avast! Licensing Alert" in the title bar) that, starting recently, now insistently pops up on every boot?... (This:
http://img18.imageshack.us/img18/7892/avastupgradealert.jpg) This one does indeed have the looks of an ad, is rather big (in a 800x600 resolution, it pretty much takes the whole screen), it indeed does not close by pressing ALT+F4 (even though, if you right-click its button in the task bar or click the icon in its window title bar, it does show the usual "X Close ALT+F4") but only by hitting the [X] in the window upper right corner, and, as I was also mentioning in
another thread, unlike before, this upgrade notification popup doesn't seem to get "disabled" by re-registering/entering a new license key (I too have tried that only to conclude it now no longer results).
To clarify, you received a key for Avast Free/Home for 4.8 for 1 year? Where did you get this from?
Also, where did your friend get the 1-year license for 4.8 from?
Then again, concerning SafeSurf's question above, I can also add, as I had also mentioned in that other thread, that I too have just re-registered my Avast Home 4.8 (just last week, on the 13th) and received too a new license key, expiring on February 1st 2012 at 00:00:00. (Previous key would expire only in summer, June or July, can't remember for sure now, but as I was saying, I went for renewal now in hope that that would, as it had before, "disable" the upgrade notification popup. Regrettably though it didn't now.) Registration done, as per usual, via the Avast website, license centre page:
http://www.avast.com/registration-free-antivirus.phpOn the other hand, and back to the Avast upgrade notification popup (in case of that being the case upsetting Carlmikael and his friend) and to "disabling" it (i.e. keep it from popping up on every boot), if helpful (eventually it may work out as a temporary alternative solution?) I can perhaps still add that the one way I could go around that was to rename the executable file that displays this popup,
asw5Not2.exe (which is found in the Avast 4 program folder,
%programfiles%\Alwil Software\Avast4\, and which I simply renamed to
asw5Not2.exe.old). I only do wonder whether doing this, renaming this specific file, bares any unwanted side effect to the normal functioning of Avast?

Also, a note to add that in order to be able to rename an Avast file (otherwise there'll be a message stating access denied) one must either previously temporarily disable Avast's self defence module (Settings > Troubleshooting > Disable avast! self defence module) or alternatively rename the file in Safe Mode (since Avast isn't running then, obviously). (Note: If chosen to temporarily disable Avast's self defence module, do remember to re-enable it back again afterwards, unticking the respective settings box.)
All in all, none of this invalidates, of course, the main advice here, which should be to upgrade Avast to the latest version 5 (which altogether rids users of the upgrade notification popup, of course) granting the best protection and as well seen that support for version 4.8 is actually due to end in a short time.