password fatigue
n. Mental exhaustion and frustration caused by having to remember a large number of passwords.
One of the tribulations of internet life is password fatigue. Use a different one for every website and you're likely to forget them. Write them all down, or use the same one, and you risk becoming the latest victim of identity theft.
—David Smith, “This week we want to know all about…: Biopasswords,” The Observer, April 22, 2007
Ask Kim Brunhuber to come up with another password and he'll throw his arms up in disgust.

"I literally reached the point of not being able to remember one more number," says the Toronto writer, whose password combinations are mostly made up of basketball players' numbers.

"One more password and I'm out!"

Brunhuber is hardly alone when it comes to password fatigue, what with all the codes needed for bank machines, online sites, home alarm systems, entry to offices — the list goes on and on.
—Jane Taguicana, “Password overload: trying to remember multiple codes causes frustration,” Canadian Press, January 31, 2007
2001 (earliest)
I think I'm suffering from PIN-code overload and a bad case of password fatigue. And it's going to get worse, because in the next couple of years we're going to stop using signatures for credit and debit card payments and switch to using four-digit codes, as part of the drive against card fraud.
—Sean Coughlan, “Don't forget to remember,” The Guardian, August 04, 2001