Question What exactly does "Keep websites secured"?

[Azurel]

Infotext for this function is

Automatically replaces expired or self-signed SSL/TLS certificates with free valid certificates from Let's Encrypt. Covers each domain, subdomain, domain alias, and webmail belonging to the subscription.

I found this "Keep websites secured" is not enabled by default in Plesk SSL It! extension

So, I have set a certificate with Let's Encrypt and this will always re-new it after 3(2?) months. Can someone explain to me why this function is not activated then? Isn't that exactly what she should do?