First go to the settings of your Avast, which is at the bottom of your interface screen to understand how to extend avast free license ?.
 
 
Here you will …
 
Open the Avast user interface
Then go to Protection
Again Virus Scans.
Run your preferred scan
Then select the file or folder you want to scan and click OK
 
If the above process doesn’t help to fix the issue then you can visit the blog to do renew avast free.