Where did ı error? License problem?

[matatug]

I have two vbulletin forum

İn other forum I can't enter admincp.I can login but login sheet direct to login page again.

And at the end of index page's link is

4b9d4bf39b50205ca672fb489ee6aae8
İs it license problem.And how can I improve ?

ı think there is no one who know it