Just bought a lifetime key, but can't multibox?

Hi, my first mouth expired today, and because I really liked the possibilities of the API I bought a lifetime plan (just one session),



But I can't multibox two accounts... the first open okay... the second give me:



_ Game Client detected

_ Authentication failed! Check is your Buddy Auth keys valid and check your sessions.



I thought that my plan supported multiclient like the site says: "Multiple gameclients supported".



So, whats the problem?

Just bought a lifetime key, but can't multibox?