How come threads are locked and restarted when they hit 50 pages, is it a limit placed by the host?

From forumotion, yes.

Ahh that's too bad. I use the email notifications to keep up with threads and they don't handle it well when threads lock and split (sometimes the links just break, other times they just stop sending updates and I "lose" the thread, etc)

Yeah, I'm not sure if anything can be done about that.

There's another forum i've been with and it uses forumotion, some threads there exceed 50 pages, maybe it can be set...

EDIT:
and actually, i saw one HERE

Yes, it can go over 50 pages, but once that *magic number hits*, threads just split by themselves.

We just leave it to page 50 and lock + make a new one so it's more convenient.

I have no idea why that exceeded 50 but it'll eventually split by itself.

For everyone's info. It's not the page number that determines this split, it's the number of post in the thread.

I've set the settings to 20 post per page meaning from this we can get 20post x 50pages=1000post. So once a thread reaches 1000 post, it will split itself into a new one.

So for example if I set the settings to one post per page, then the maximum page will be 1000 before it splits up.

So it's not the page number, it's the number of post in the thread. And the one who set this is Forumotion and there's no option for it to be changed by the admins.