To settle 6 yr old charge off or not

I have a charge off credit card with a company (Capital Management) claiming to represent the credit card company (Capital One) wanting to make me a deal to pay it off at half the owed amount. This is a 6 yr old charge off entry and I have been told it will go away after 7 yrs?

Also I am aware that the charge off will stay on my credit report and with a status of settled which may or may not help my score. If I pay I think it shoulf be in full but then I have to police them to ensure my credit is repaired in such a way that my score is improved or better the occurance on my credit report is gone.

I'm a little leary that they are aware of the 7 yr limit and are just trying to get what they can before they run out of time. That paying this card off which was $300 when I stopped using it and now is $1300 would be a mistake. So I have one more year or I am assumeing. How accurate is my assumption?

So My questions are:

1.) Will it go away after the 7 yrs is up - even if they are still trying to collect (AKA is 'last activety' defined as when card was used / closed or last collection activeties?).

2.) Is there any way it can come back if it does go away?