Hi there,
Thanks for reaching out to Adobe Community.
As per my knowledge you can use the exact code line mentioned the above link. As it is written there, "the value is added to the existing value" which means that if you start with nil it will keep on adding the counter.
See this for definition:
https://marketing.adobe.com/resources/help/en_US/reference/lifetime_value.html
It can be the total value of line items from start of tracking on your Web page.
Thanks!