When you buy apps in volume, you can distribute content directly to your users using redeemable codes. You can also use managed distribution to assign apps to users on iOS 7 or later or OS X Mavericks or later using Mobile Device Management (MDM).
Before MDM is used to assign apps to users, you must link your MDM server to your VPP account using a secure token. This secure token can be downloaded to your MDM server by accessing your account summary from the VPP store.
For users to participate in managed distribution using VPP, you need to invite them first. When a user accepts an invitation to participate in managed distribution, their personal Apple ID is linked to your organization. Note that the user doesn’t need to tell you what their Apple ID is, and there is no need for you to create and provide Apple IDs for their use.
Once an app is assigned to a user using MDM, it appears in the purchase history of the App Store for that user. Apps assigned using MDM will not be automatically downloaded onto devices with automatic downloads enabled. The installation command must be sent from the MDM server.
When you purchase content from the VPP store, you are offered the choice of managed distribution or redemption codes. Use this chart to help determine which of these options is best for your institution.
Click here to read more about How to use managed distribution to manage VPP apps to users (Apple Support site).