Here is the EULA for avast! Free Products:
http://www.avast.es/pdf/eula-avast-free.pdfAnd this is the important point:
2. Permitted Use of the Software
You may install and use the Software on an unlimited number of computers. The Software must be used exclusively by you or members of your household solely
for private non-commercial purposes. You may also make one backup copy of the Software.
ANY USE OF THE SOFTWARE OTHER THAN AS EXPRESSLY AUTHORIZED BY THIS SECTION OR ANY RESALE OR FURTHER DISTRIBUTION OF THE SOFTWARE CONSTITUTES A MATERIAL BREACH OF THIS AGREEMENT AND MAY VIOLATE APPLICABLE COPYRIGHT LAWS.