More than one million players paid for the new Call of Duty Elite service in six days of launch, according to Activision.
Launched on November 8, more than four million players have registered for the service, despite overwhelming demand which has crippled online servers and support.
Premium memberships for the service cost $49.99 and allow players access to all features such as downloadable content, maps, competitions and virtual items.
"The demand for Call of Duty Elite at launch was so overwhelming, that for the first several days, the service did not perform up to our or our fans standards," commented Eric Hirshberg, CEO of Activision Publishing. "I want to personally thank our fans for their patience.
"Our teams have been working around the clock to get the service scaled up to meet demand. I'm very pleased to announce today that the service is now performing stably and anyone who wants to try Call of Duty Elite is now able to do so.
"Due to the scaling challenges we encountered at launch, we are giving all Call of Duty Elite premium Founder members an additional 30 days of the service free of charge."
Activision noted that while Elite hit one million paid members in six days, comparable premium subscription services from Netflix and Xbox Live took approximately one year to reach a similar milestone.
More than 80,000 Call of Duty Elite clans have been created and over 100,000 user-generated videos have been uploaded to the service, which is seeing three million daily logins.