The verb expend means to use. If you expend all your energy raking the leaves, you may be too tired to play hockey afterwards. Better pace yourself — you'll never get all of the leaves on the ground, after all.
The verb expend means to spend or pay out. You can expend money, but you can also expend things like good will and time. As a voter, you can vote for or against the city's plan to expend money on a new library building, but the city may be expending voter willingness to support the plan if the building goes over the budget. There is no point in building a library if they can't afford to buy books!