Directly from the developer
https://www.astronomie.be/registax/download.html
Most people doing planetary imaging these days use AutoStakkert for the main processing, frame selection and stacking, and then import the resulting stacked image into Registax and do the final sharpening using its Wavelets feature.
https://www.autostakkert.com/
Having said that, your DSLR is better suited to deep sky imaging. For planetary imaging you're better to go with one of the ZWO planetary cams which will give you a much higher frame rate (but much smaller field of view).