You seem to have misunderstood.
...at which point you may renew or switch to free protection, the antivirus behaves otherwise normally.
I didn't misunderstand. I just didn't think it through. My apologies.
The Pro version has more protection, the free version has less protection. If your paying for the Pro version, I would assume you are in need of its extra protection.
That protection will stop functioning once the subscription expires.
SafeZone: Secures shopping & banking
Sandbox: Lets you surf the web virtually
Sandbox: Runs risky programs virtually
Firewall: Blocks hacker attacks
Firewall: Secures personal data
Firewall: Secures your identity
Anti-spam: Stops annoying SPAM
Anti-spam: Blocks phishing scams
So your hacker blocker will revert to the Windows default, slightly lower level of protection.
You will be left with whatever browser security your preferred browser has.
Your programs will be left to run in whatever security level your operating system offers.
You will be left to your own to avoid phishing and identity theft scams, and SPAM. (No protection)