One upgrade expiry dates, I did find this on the Air Canada eupgrade site: "

• All credits are valid through the Altitude benefit year, unless otherwise specified on your eUpgrade account. The 2017 benefit year runs to February 28th, 2018. Furthermore, all credits earned on or after November 1st, 2017 will be valid until February 28th, 2019."

Of course, I am not sure if the "earned" date is the same as the deposited date - or were the credits earned when you were granted your status or when you selected your privileges. I'll find out I guess...