Mac:
!Important: To use these commands JDownloader must be installed from .dmg file. Installer won't work with this!
Copy these lines into your terminal and press enter:
cd /Applications/jDownloader.app/Contents/Resources/Java
sudo java -jar jdupdate.jar -branch NIGHTLY
Then you are asked for the admin password and the update will get started.
Once the update is done you can quit the terminal by entering 'exit' and start JDownloader as usual.
Now you can enter your rehost.to credentials as premium account, restart JDownloader and start downloading.
Linux:
Open a terminal and change directory to JDownloader directory:
cd /home/%User%/.jdownloader
java -jar jdupdate.jar -branch NIGHTLY
Afterwards you can enter your rehost.to credentials as premium account in JDownloader, restart JDownloader and start downloading.
Windows:
1. Get JDownloader from
JDownloader.org and install the programm.

2. Right click on your JDownloader shortcut and click on 'Properties'.

3. Add ' -branch NIGHTLY' to the 'Target'.

4. Start JDownloader and click the 'Check for Updates' button.

5. Restart JDownloader.

6. Add your rehost.to Premium Account and restart JDownloader again.
IMPORTANT: Delete all expired or none-premium accounts from the account list first!
IMPORTANT: If your password contains special characters please change it to avoid that JDownloader shows your account as invalid!
7. DONE! :)