If you need a permanently free antivirus, use or Windows Defender instead of cycling trials (which violates terms).
Bitdefender does not have a permanently free antivirus (except for a limited "Bitdefender Antivirus Free" for Windows, which is a separate, basic product). The "Free Trial" refers to a fully-featured, premium version (usually Bitdefender Total Security ) that works for 30 days without requiring payment information upfront in most cases. bitdefender free trial download