MAYBE there might be a way to ascertain that avast IS still working for those who fear that it is not after registration has expired.
There IS a way to test to see whether Avast is still working AFTER its registration has expired. Create an EICAR "test virus" file. The file is NOT a virus, but Avast--if working--will react as if it is a virus.
Create a simple text file and insert ONLY the following string:
X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*
If you save it and NOT end it with a hard return (68 bytes), it will be detected as the EICAR Test String.68 "virus" (68 bytes). If you save it AND end it with a hard return (70 bytes), it will be detected as the EICAR Test String.70 "virus".
Give it the .doc extension (because the default in Avast Free is to put .txt files on the File System Shield's exclusion list).
Play around with this BEFORE registration has expired (so that you know how your version of Avast is supposed to operate). But when you do (before registration has expired), turn OFF your File System Shield (and other applicable real-time protection) when you're creating and moving the test file (so that it doesn't get destroyed before you actually run the test).
Then, following expiration, run through the same testing procedures to see if Avast is giving you real-time shield protection. My bet is that it isn't. (I'll run the test for myself in 10 days after mine "expires" again. Unfortunately, upon my first expiration, I hadn't yet had the insight to run some "test virus" tests before I re-installed.)
When you post back here the results of your "following expiration" tests, PLEASE mention which version you were testing.