I would like to release my POS software which has some commercial value.

Our business use a localized commercial product which cost us 400 euros. it locking up the keyboard, lack features and work in windows only. That's why my program is developed, it use some interesting modern technology.

I believe that open the source could bring some future to this program. However, I am stingy. I would like to put some restrictions:
- As the original developer, I would not like to see other people copy my software and sell it. They may charge service for installation or maintenance by not selling the software.
- Freely available in form of source code or binary package. I should be the copyright owner and they should not remove the copyright notice.
- Free to modify, but I hope that it would not branched off without my permission so I hope that modifications would be submitted.
- Although I don't think it would be the case. I would like to reserve the right to sell a commercial license at minimal cost of about 20 euros if a reseller want to bundle it with hardware. I would like to take the adventages of submitted modifications even if it go commercial in the future. The free version and commercial version would have no difference except the license.

What kind of license should I use? MPL+commercial? If I use MPL+commercial, then it could not be hosted on sf, right?

Sounds like a plain GPL license would be fine for your needs.

As the copyright holder you could release the free (as in freedom) version under the GPL, and also offer the program it under a different, proprietary license. I believe several popular open source programs are licensed this way (Qt, MySQL, etc.)

This negates the GPL unless it's just a simple request that isn't legaly binding.

Just go proprietary.. if it is good like you say.. make some money off it. GPL it later.

If you say it can't be branched off, how is it open source? You can't use the GPL for that product. You might want to go the dual-licensing route as others have mentioned - it's working for the Qt libraries, KDE, mysql, SugarCRM and countless other products, so it may well be worth considering.

Don't be surprised if another company pops up with a better version though - look at SugarCRM (an EXCELLENT product) and vTiger (an even better one!) for example. It can serve as incentive to keep you on your toes and keep the product extremely polished, but if you're lazy or if you lower the priority of the project, it can spell the end of income from that particular product.

it seems that MPL is probably the better one. By sharing the commercial interest to others, I can get back the modified code. It's a fair license and the project would evolve better than GPL.