Normally, if it was an approved work-related  expense, it must be reimbursed whether or not you are still at the company at that time or have left it; and if you have left it, whether or not you left voluntarily (e.g. quit or resigned) or involuntarily (e.g. fired). The exception would be if there was some employment contract, either an explicit one (such as an actual employment agreement between you and the company) or an implied one (such as a firm policy, known to employees and consistently enforced, in the employee handbook), stating that if employees leave voluntarily, the forfeit reimbursement. If there is a contract to the contrary, the contract's terms will control; otherwise, you should be reimbursed even if you leave.