peesonally, to me it doesn't matter. bought or not they get on the list.
Crim has two lists, one for clans that have the system and one for those who do not
I think it stays unless the owner leaves and is the last person. It might get disbanded. But If there is still one person in the clan I think the clan won't dissapear.
But clans can go inactive.
Eg. CHAOS
That is why chaos reborn was made
CHAOS went inactive. So the active people left to go to chaos reborn