I had this last month, it writes to an about.php, and the .htaccess file stays in the server's memory so you have to constantly delete the file sit rewrites, and flush the memory, it cost me two weeks of constantly fixing, lost revenue and I lost 2 clients. I eventually paid for Securri and they sorted it out. My advice is on Black Friday and Cyber Monday see what plugins you can get for cheap and start buying them if you can, nulled plugins can have malware in them, I only use them as demos so I stop wasting money on plugins that don't work