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As soon as she got her paycheck, she spent the whole thing.
Literal
She [topic-は] paycheck [object-を] receive [as-soon-as-とすぐに] used-up-completely [ended-up-てしまった].
Three productive endings stack here. The compound 使い切る pairs 使う ('use') with the auxiliary verb 切る ('cut') — used as a productive suffix meaning 'completely, thoroughly, to the end.' Add ~てしまう and you get the implication of regret or finality: she didn't just spend the money, she blew through every yen. The temporal frame ~とすぐに ('as soon as...') uses the conditional と as a tight 'when' clause, with すぐに ('right away') making the immediacy explicit. The combination paints a vivid picture of impulsive spending — paycheck in one hand, gone the next.