As far as I know the PRO version is still available. I recently reinstalled DVD-Pro and got my PRO keyfile from my email address. I registered literally years ago
Sometimes there can be a delay between registering and getting your keyfile, depends how busy he is, but a quick email usually gets it much quicker than waiting for him to update the DVD-RB Pro keys
I've tried a few similar software but always go back to DVD-RB Pro. Its not as fast as some, but thats for the reason of HCEnc and quality is better than speed. It also fixes some DVDs that simply won't play correctly, but DVD-RB Pro fixes any crappy authoring errors by companies rushing out cheap DVDs
If you are also interested in video to DVD, have a look at AVStoDVD. Similar idea but accepts pretty much any video file source and converts it to a true DVD, with menu if needed, and also uses AviSynth and HCEnc so teh quality is about a sbest a syou can get. The fact that it supports AviSynth is a BIG plus point. I also have VSO ComvertXtoDVD but don't use that much anymore as its so slow compared to AVStoDVD even if using AviSynth filters
https://sites.google.com/site/avstodvdmain/
You can also use the last version of HCEnc 0.28, just replace the one in the HCEnc folder with the one from HCENc 0.28, BUT you NEED to rename it from HCenc_028.exe to HCbatch.exe for it to work
http://hank315.nl/
You can also update the included AviSynth to the last release, I think its 2.60 as I use AviSynth+ instead for true multithreading and improved filters
https://www.videohelp.com/software/Avisynth
http://avisynth.nl/index.php/Main_Page
Just loaded up DVD-RB Pro and its now recognising AviSynth+ as installed, that used to be a royal pain to get to work, but I guess the AviSynth+ installer does a much better job than it did when it was first released
AviSynth+, in my opinion, is much faster and has a LOT of multi-threading support now built-in instead of a hack. Also, a LOT of older and new AviSynth filters have been updated with bugs finally fixed or improved and also now available in 64-bit versions
https://github.com/pinterf/AviSynthPlus/releases
https://forum.doom9.org/showthread.php?t=175170
https://forum.doom9.org/showthread.php?t=168856