The packs -- available in 10-day, 30-day, and 90-day flavors -- double all experience and tokens earned for the duration for all characters on an account. Not coincidentally, the 30-day boost costs just under $15, the same price as a monthly subscription in most subscription-based games. Each boost runs for the specified length of time and is activated immediately upon purchase, which makes the benefits and drawbacks rather transparently obvious. Players of Global Agenda can purchase packs on the official site, with a small guide available for the new feature.
[Thanks to Caleb Goh for the tip!]