Instead, she deposited money into the social club account on 217 occasions, before withdrawing it by writing cheques, forging a second signature, Judge Moran said.
Keenan defrauded the company of $457,639.95, he said.
Counsel Max Withers said it was a "something of a relief" for Keenan to finally be discovered.
"She is fortunate, however, that she does still have her family's support. They do not condone what she has done, and they have made it quite clear to her," Mr Withers said.
Keenan had stolen from an employer who was good to her, and she admitted she should not have done that.
Keenan had no means to repay the money, he said.
Judge Moran said Keenan had a role where was trusted with the company's money.
"They relied upon you implicitly not to rip them off. Unhappily, their trust was misplaced," he said.
"Heaven knows what you did with all this money ... The amount you defrauded the company was huge."
Judge Moran said he accepted Keenan was remorseful and had co-operated with police and owned up to what she had done.
The judge did not order reparation as the prospect of her repaying the money was "a forlorn one".
"This is a dark day for you. This is a dark day for your family."
