Also - If possible, you should let people use the software as a registered version for now, and rather charge for it in a future version, or give people 1-2-3 months free full versions. -If you need reg. version to actually trade with it that is.
The unregistered limit should nevertheless be raised to something like 1-3 hrs instead of 10 mins.
I am a very small-time trader with only 2-3 BTC, but might pay .1 BTC if I found that I wanna use it for some time forward. But paying up-front for something without a name in the community is really not gonna happen. Actually I think you would make more if it was "donate-ware" but I might be wrong on that one.
I'll look into loosening up the demo restrictions and increasing the demo version timeout in the near future. The demo does allow you to place bids, but they're limited to .1 BTC or less each. Giving people a fully functional demo version for a week or two after initially downloading it could probably be implemented without too much trouble and is something I will consider.