This is how my own business model works:
The Business Model is quite simple. It consists mainly of
public passion - Once there are people who use your component as an integral part of their own business,
they will be able to care about you. This is what happens with the AEC and I guess similarly with other Software - People see the work that is put into it and when it is, to their taste, sufficiently good, you have completed the first step -
they like your software.
The second step is to let them know that
it is hard work (as indeed it really is). This can only go through a lot of public discourse, like public forums, where you communicate that you work hard. If you were a farmer or somebody baking bread, the people would see you working hard and appreciate it. So we have to transfer this into the software world - drop some remarks on how you worked another night until 5 am or did your best to put customer wishes into the software. Once people get this, they are ready to give something back as appreciation of your work.
And now comes the presence of memberships - your work is continuous, as is your customers use of your software. Everybody will know that, so using memberships on a rather inexpensive level will be only natural. But you need your users to see that they can support you. This is why we have a one month free subscription (that they can always come back to of course) and several longer time memberships for payment. So each month, our users will come back to the point of having to
decide whether they want to support us or not. If you made a
little bit right in the previous steps, chances are that more and more users will feel
for your work and be inclined to get a membership, if it is not too costly of course

The next step that I am currently preparing here is special service for subscribers, as there is currently no real benefit of being a subscriber. I am working on a way to provide on-component support that will create a direct contact from the customer to my desk without the need to go over forums or even email. This support will depend on the membership level of course - when there are more support requests at once, the ones with a higher membership level will get support first. Another thing that one can have are different forums for different priority, although I'm no fan of open separation. I'd rather have each user individually see that there is a lot of work (which is why the support queue list will be public, yet anonymized, so that users can see where they stand) that needs to be done.
If there are developers interested in this, please contact me, I have started working on this and it will be Free Software and have various APIs that you will be able to integrate into other components - in other words, I need help

However, from that point, you have gotten yourself out of the proprietary loop and the number of users will culminate. On globalnerd, we started off with about one new subscriber each week - that was last august - then at the end of last year, we had a new subscriber each day, currently we are between one and two subscribers each day. About 10% of our registered users (3,5k) are subscribers. And about 20% of them even use PayPal Subscriptions or regularly go to the paid plans, so users paying more than once is far more regular than one may think.
Apart from that, I don't have kids - this is always the thing that I have to admit later in such discussions. Quite on the contrary, I spent some time in the middle of last year trying to figure out what kind of life I want to lead. I figured I'd rather live off the good will and appreciation of my customers. Of course, this is a tough position as anybody could come over and steal my job. But this is mainly a very good motivator

The recent developments show me in which direction it is leading me, and I hope that in the future, this will continue in this direction. I will have all benefits and all downsides of being an idealist so to speak. At least I'm somewhat in control of that fate... It is a tough road anyways and it is even harder to introduce this way of doing business
late in the game.
That was mine, how about yours?

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Developer of the AEC Membership Management Component:
http://valanx.orgFellow of the Free Software Foundation Europe (and so can you:
http://www.fsfe.org !)