A thread lasts as long as you need it to. If there have been no posts for long enough, though, it may be archived.This is the first time I've used a forum, Any forum, How long does a thread last, If I have more Qs. about other topics do I start a new one (after I search, Something Else I need to learn more about), Or does this one go on and on? Do you ask 1 Q. at a time?
You can continue to discuss what you like on the same thread, as you have done, if it is loosely related, but if you're back with a completely new thing to say it is better to start a new thread. This will give your conversation a relevant subject heading and then becomes something that can be more easily searched for at a later date.