I'd like to suggest to the developers of simfy that their desktop application be submitted to the Software Center. How should they go about doing this?
From Ubuntu App Developer:
Selling software and content
Can I distribute and sell proprietary software through Ubuntu?
Yes, you can distribute proprietary software through Ubuntu by joining the Ubuntu Application Developer programme. In some cases the software is provided without a charge, and the developer makes money through advertising or upsells. In other cases a software license is sold to the user giving them rights to the software. Both systems are allowed in the Developer Programme.
You should ask simfy devs to go to this site.
Here's detailed information about submitting new packages to Ubuntu