The phrase "anniversary issue" refers to a special edition or publication that celebrates or marks the yearly recurrence of a significant event or milestone. Full definition
The nine issues are mostly dated 1990 and 1991 but there is a 10th anniversary issue dated 1987! (gardenhomeandparty.com)
In this 30th anniversary issue, we both look back at the science of the past 30 years and look forward at what discoveries will come in the next 30. (discovermagazine.com)
I think this second anniversary issue has quite a lot to offer. (totalpolitics.com)