istrošiti

1. to use up; to spend
   Istrošio sam sav novac već prve nedelje. — I used up all my money in the very first week.
   Baterija na telefonu se brzo istrošila. — The phone battery ran down quickly.
2. (of objects) to wear out
   Za godinu dana je istrošio dva para patika. — He wore out two pairs of sneakers in a year.
   Kočnice su se potpuno istrošile. — The brakes are completely worn out.
3. (istrošiti se, of a person) to burn out; to become exhausted
   Posle deset godina na tom poslu potpuno se istrošila. — After ten years in that job she was completely burned out.

The imperfective counterpart is trošiti.