JordiCP that is a interesting way to go. The only problem could be if the user transfers devices (say 5 times in a year - for whatever reason - that would be a lot of subscriptions to parse [subscriptions are not consumed but expire]) otherwise I would have the managed item and the subscriptions
JonPM: This Google Doc:
"If you are using the Version 3 API, you can also consume managed items within your application. You would typically implement consumption for items that can be purchased multiple times (such as in-game currency, fuel, or magic spells). Once purchased, a managed item cannot be purchased again until you consume the item, by sending a consumption request to Google Play."
To me this reads when they want to transfer I consume the item and have them purchase again
As for Violates Google's Policies - I have not (as of yet) found anything that says this is a No No - If you have found something please let me know
BobVal