License key is damaged- Adobe Digital Editions

[georgiat39620735]

I have purchased a book and have read it many times in the past in the library of Adobe Digital Editions. Now it says it is unable to open this book because license key is damaged. Is there any solution to this problem? I do not remember from which site I have downloaded it. (I have a PC)

[defaultsbuo55ytabm9]

I have the same problem. I can load a book to the PC, but I can´t open it. "Unable to open xx. The license key is damaged". Guide me, please!