Every member of the House of Representatives serves a term of 2-years,
and every one of the 435 seats is up for election after 2 years.
As long as the Speaker keeps getting re-elected to his seat in the House,
and as long as his party keeps a majority of the seats in the House, and
as long as they want to keep electing him as the Speaker, there's no limit
to how many terms or how many years he can keep the position. But it's
always 2 years at a time.