Reports of Xbox Live subscribers Gold memberships randomly disappearing have been appearing on Xbox official forums. Not only have some users reported that their Gold membership has vanished, but also their Gold Tenure shows 0 years regardless of the number of years they have been a gold member.
The cause of the problem according to Xbox Support is when users 'stack many codes that are redeemed'.
Apparently if you were to redeem for instance x3 12 month XBL Gold membership codes to take your membership expiration to 2017, then you may be affected by the issue of disappearing Gold membership.
As of right now there is no known fix for this problem and its something only Xbox Support themselves can fix, so if this happens to you then contact support right away.
Let us know below if you have been affected by this problem...