I did send the log 2 times when having a remote session with JD developer. JD is great and developers should think of re-writing this soft for non java and make it handling cookies in proper way. IDM is just so so alternative, definitely not one in all solution like JD.

Today I found out a program called Mipony. I am amazed to be honest, great piece of software. It can do everything JD does, except multiple connections per file... Considering how young is this program, it should outperform JD sooner or later if only developers are motivated enough. And it doesn't have any problems storing my premium details, unchecking it automatically or anything like JD does.

So if browser / IDM / Mipony can handle FS premium properly, why JD can't?

The problem was reported more than 2 months ago in this thread. But if you check carefully also other hosters, users from different countries report exactly the same issues with JD. That makes me thinking it is 100% JD bug, might be related with Java or the way Java handles (or even not) the cookies...