Unfortunately this is not possible. All emotion purchases are linked to either your Apple iTunes Account or Google Play Store Account. The benefit of this is that you can access the emotions on any Vent account while you're logged in on your device, however because the purchases are linked to the app store account they cannot be transferred.
Gifts are handled differently. They are linked to a specific user account in the app, so can be accessed on any device as long as it is logged in under the username that received the gift.