How can I get a discount on Roon lifetime price $699

Crap or get off the pot.
The lifetime script will eventually be gone at any price. They just offered it for startup cash.

The only thing that ROON does (I think) is check the license when you start up the program. If ROON goes bankrupt that license check would be the only thing that would stop a person from still using the application/server.

Now if ROON were to put the source code in escrow for lifetime members then a patch could be created easily. That won't happen though.

I bought lifetime subscription at $499 long ago and would easily buy again today at $699.

I was a DA and paid by the year for two years before buying Lifetime. It's Netflix and Wikipedia of music with DSP, favorites, playlists, suggestions etc mixed in. I would have never discovered the Artist's and music I have without Roon and Tidal. Worth far more than the asking price IMHO. 

I agree totally on all the sentiments expressed on its useful side.

But as I have said tech is so rapidly changing these days I just don't see it staying the dominant force forever.
Hence my yearly subscription for now.