Multi-device support for non-renewing subscription

Question

I'm working on a news app. All news items are fetched from my website. To make a bit of a profit out of it and keep the website running, I implemented some ads. Now, I'd like the user to be able to turn off all ads in the app for a few bucks. I want to provide this option on a yearly basis. So, this year there will be a button in my app, reading something like "No ads in 2013". After paying, the app will be ad free for the rest of the year. In 2014, ads start popping up again and the user can buy the product "No ads in 2014", for the same amount.

I figured a non-renewing subscription would be the way to go here. A few things I haven't figured out yet:

1. Is it possible to automatically change the name of the in app purchase over time such that it reads "No ads in 2013" in this year and "No ads in 2014" next year, "No ads in 2015" after that, and so on?

2. Apple states that it is the responsibility of the developer to implement multi-device support. Ok, fair enough, but I haven't found a way to identify a user yet. Users don't need to be logged in to use my app and as far as I know, there is no way to get hold of the user's iTunes login name. How can I transfer the product to a user's new iPhone for example?

Answer 1

After much thought my conclusion is that there is no way to achieve this without bothering the user to log in in some sort of way.

The alternative I came up with is this:

I just create a regular non-consumable in app purchase, with the year embedded in its identifier. This way, in code I can check the identifier against the current year and determine if the user should buy the product with identifier "year + 1".

As non consumable purchases are linked to the user's iTunes account, they are automatically transferred to other devices like a new phone.

Only thing I must not forget is to create a new product for every year to come.