Bread-Bakers v100.n069.7

I purchase my active and/or instant yeast in 1 pound packages. I'm given
to understand that if kept and used directly from the freezer it will last
a much longer time without harm. My question is how long can the yeast
SAFELY remain in the freezer without worring about it. I don't proof it
just use it. I've heard one year but i have some stored away longer.
PLEASE HELP ME OUT HERE....

Thanks in advance.
Mike