Jorge,
I've never had any problems just leaving the DLLs declared for the rest of the app lifetime, it's not like they have a huge memory impact.
>Is there a way to clear only one DLL? I understand that isueing CLEAR DLLS will remove all functions that I have registered, well, anyway is there a reason that I should release the dlls if the aplication is not using them anymore? will I have more free memory or what?