We sell a desktop app with an involvement in dev and support of about 0.25-0.50 FTE, with revenues in the range of $50K/month although it was launched 9 years ago and the first year was only about $2K/month. The server side is just one Windows 4GB server for user signups, billing and license validation. One good thing of desktop apps is that the server side is so cheap, you are basically selling IP.
It has this features:
* B2B in a niche market (TAM < 100K-200K users)
* Some viral component so you do not have to spend money on ads for growth.
* Sold as a subscription and only as a subscription. Don't innovate with licensing focus on product, this is important. When users have fewer buying options, they decide faster. That's why Steve Jobs reduced 50 Mac models to just 3.
* When the subscription ends, the application must stop working. This is also very important. You want your entire user base to be able to install the last version. You do not want to support older versions, you only want to support one.
* Has to have a very generous trial so that users have time to find use cases with your product. Better a trial based in actual usage instead of exploding trial base in calendar days. You want your users to actually use your product and depend on it.