When you install, you get a 3-month trial period.  They say the
license will extend itself for another 4 weeks but it then goes into
"demo" mode (you'll see "Key expired [DEMO Mode]" in the update
report).  That means it will detect but not disinfect (i.e., it
becomes worthless).  After expiration, you don't get any more
signature updates (i.e., the product goes dead and can detect only the
old malware).  Then you have to buy the Personal Premium version
($27).  You could save a partition image before installing AntiVir and
then restore it after the expiration to again install AntiVir but then
you lose any other changes made to that partition over that 3-month
interval.  AntiVir was a good product until Avira got their hands on
it and fucked it up.

I knew there were reasons why I dumped Avira's demoware.  Not
interested in popup windows (i.e., banners), especially when they
interfere with other programs.  Not interested in trialing an AV
product for just 3 months whereupon it becomes crippled for another
month and then it stops accepting sig updates.  Freeware it is not.
Demoware it be.  Not interested in self-destruct software.

Note:
AVG also has a banner but also an option to turn it off.

The free versions don't have all the features testing in the
av-comparatives report.  For example, the free version of Avast does
not include script blocking.  If you just look at the average of
Windows and macro viruses (what Avast can handle), Avast is 97.01%
versus 94.46% for AVG.  I can't tell if AVG includes script blocking
(no option to configure it).  Avast is much more configurable than
AVG.  I can run AVG using a command line so I can use the far superior
options in Task Scheduler rather than the scheduler included in AVG.
Alwil says their Avast doesn't have a CLI (command-line interface).
Either AVG or Avast will do you well.  I can't tell how well Panda's
AV works.

I have Avira Antivir PersonalEdition Classic loaded onto one of my lab
machines. It is bannerware but it is _NOT_ crippleware. It has been
running succesfully for well over a year with full updates and no
license timeout. I don't know if this is something that has changed
since you last used it. Yes, the banner is annoying but I have found
detection rates to be excellent, better than a lot of the commercial
A/V. It is the product I have recommended to home users within my family
and friends. I have no experience of it in it's commercial clothes -
they would not provide the commercial version for my lab - I may ask
again. :)

I was put off AVG some time ago when they used to have updates only once
a fortnight for the home version - I am reliably informed that they have
changed the policy on this and now provide daily updates but it's
difficult to forgive and forget - the same as you with Avira, I guess!

IMHO, the detection rates with Panda are dismal. (comparitively speaking)

Do you have any experience of submitting virus reports to any of the AV
companies? I have had mixed success from AV companies but the response
from Avira has been excellent, only surpassed by Sophos and don't get me
started about McAfee!

It is unclear what exactly happens when AntiVir goes into DEMO mode
but it does happen after the 3-month trial.  I suspect that you don't
get program updates in the 4th month but still get sig updates (but I
had their latest version so there were no program updates to retrieve
to test).  I've seen many posts by other AntiVir users who complain
that their last signature update was sometime before the trial
expiration; i.e., after the trial expires then no more updates.

If it weren't for the banners and the expiration then I'd be using
AntiVir (free version).  I just removed AVG (free) and put in Avast
which consumes twice the memory (real + virtual) of AVG: 3.3MB real +
37.1MB virtual for AVG, 41.7MB real + 41.1MB virtual for Avast.  There
are several features of Avast that I like but it definitely consumes
more memory.  Hopefully another 40MB won't matter with 2GB real RAM.
Unfortunately I've had several more false positives with Avast than
with AVG.  I understand why the false positives on the Nirsoft
utilities but not why on the .vdmk files for the VMs in VMWare (which
are base OS installs with no other software, like Windows XP Pro SP-2,
Solaris 10, and Fedora 7).  For AVG, I could schedule an on-demand
scan using the command-line in a Task Scheduler event (the schedulers
suck that are in AV products) but the ashCmd.exe for command-line
access to Avast is missing in the free version.  I can run
"ashQuick.exe c:\ d:\" to scan my 2 drives but it halts on a detection
(even a false one) so it is worthless for scheduling a scan when no
one will be at the host.

I suppose that eventually I'll have to abandon the freebies and get
the commercial versions.  Oh joy, then I get to trial all the
commercial versions to compare them against each other.

- Download latest version of AntiVir.
- Download new hbdev.key file.
- Install Antivir but choose to NOT do any updates (so they'd be
available later since never applied yet).
- The product's status says it license expires on 11/30/2007.
- I set the clock ahead to 12/14/2007, two weeks after the expiration
and supposedly within the 1 month extension.
- Rebooted the VM.
- Tried to do an update.
- The update failed with "no valid license key" and "key expired [DEMO
Mode]".