(Sorry for my English…)
Can I use (in source files) samples and vsts which I bought? Something like Vengeance or Sylenth1?
Hey, my best solution to that is to make clean sample of the bought instrument, with no delay and reverb make it as a wav, and extract it to your channel, then put your effects on.
Sometimes a half bar is enough to do the trick, or even a whole bar.
Best to keep source files clean and without any other instruments than those you can use when you get a demo version, espially fl studio.
Is there free .dll files do a description .txt file to explain where to put the .dll files into. Only 100% free plugins 
hope this gave you some answers 
Thanks for reply, it was very helpful, but making samples as a wav is not an option for me.
My favorite plugin is 3xOsc, but I don’t like to do pads and strings on it, I have some free vsts but the best vst for strings is Sylenth1.
Well, I have to correct two projects before upload. Thanks thanks thanks… 
If i understyood you correct in (source files) it is only allowed to upload projects where midi tracks are included and plugins they came with your DAW . 2 weeks ago i got a file rejected.I used many vst instruments and hardware for the project so i decided to render all tracks to audio seperatly for the project.Only audio files where inside to be possible for mixing. Good luck!
