Yes, you can't uninstall it, while it goes away for the session, it just reinstalls itself when you open the browser again, or it never uninstalls it in the first place.
Edit: You can remove it Manual and it will stay removed.
You have to go under
C:\Users\ USER \AppData\Local\Maxthon\Application\User Data\Default\Extensions
and delete the corresponding folder there. it will be folder with random letters, but the folder should contain a folder with "0.1.3_0".
This for now removed that plugin completely.