Redeeming a Star Trek Online - 12th Anniversary Pack key is really simple, just follow these steps:

1. Head to www.arcgames.com and log into your account. 
2. Redeem your code here: LINK

The key is not working 

If you have activated the key according to the guide but the code appears not to work, please check what type of error message you receive and depending on it follow the appropriate instructions: 

• My key is Duplicated / Already used
• My key is Invalid
• My key is region locked / can't be activated in my country
• My key activated a different product
• My key did not activate all of the content