GP+ subscriptions are year-by-year and so 2016 subscribers should remember that at midnight on December 31, the subscription ends and access to the magazines will be finished. The codes will no longer work.
If you wish to keep the magazines, you should therefore download them all. After the New Year, access to the magazines will be via the archive alone, and that will require another payment.
Similarly, access to the archive will be changing at the same moment, so those wanting to complete their collections should download all the desired magazines before the end of the year.
This will not affect 2017 subscribers.