Pure Music went into "demo mode"

Purchased Pure Music about 5 months ago. Upgraded to 1.86 last week and have been using it since. While trying to get rid of the annoying "clicks" heard throughout a song, I somehow removed Pure Music from the dock and when I brought it back Pure Music is saying that I'm in "demo" mode. Pure Music says they have old fashioned telephone customer service. I called twice and have had no answer.

Any suggestions about the "demo" mode or how to fix the "clicks and pops" while listening? I'm using an M2Tech hiface usb/spdif converter with a Mac Mini.
If you hear clicks and pops, that suggests you did not use a bitperfect ripper to extract audio files. Using Pure Music won't fix this.

You should use a bit perfect ripper like dbPoweramp, XLR, or Exact Audio Copy to re-rip those files that have errors.
Simorgh: Sorry. I did not mention that I've been listening to music on my hard drive for two years via optical output with no issues. I added Pure Music five months ago and had no issues as well. As soon as I added a usb/spdif converter, that's when I started hearing the clicks and pops. BTW, I called Pure Music and they sent me my registration info. I added it again and I am out of demo mode, but I still have the clicks and pops when using the usb/spdif converter. I have to listen via optical until I find out what is going on.