VPP license transfer
it looks like I haven't been the only one wondering about "owning" the license to an app and being able to reassign it.


  App Store license management.
  
  The App Store Volume Purchase Program now offers businesses the ability to assign apps to their users while keeping full ownership and control over app licenses. Companies purchase app licenses through the VPP website, and can use their MDM solution to assign apps to employees over the air. [...] Apps can be revoked at any time and reassigned to other employees. [...]


http://www.apple.com/ios/ios7/business/