Trialware is a great idea. You download an application and use it for a set period of time and at the end it becomes crippled or won't run at all. The trend seems to be to make the trial period calander based, that is you have a set period of time to use it from the date you first installed it (or in some cased first open it).
With my newfound User eXperience hat on, I have a much better idea. Let's make the trial time a bit shorter, but have the trial actually track the usage. How many times have you installed a trial then not looked at it for another couple of weeks, and then a month goes past and you try it again to find it has expired. Has the user had enough time to get a feel of the program? I know when this happens to me I usually don't bother buying the program because I don't know if it is for me. Why should the user spend the time to get to know the program on the program's terms? Wouldn't it be a much better experience if the program said "how much time do you want to try this out?" Let the user choose if they want one or two weeks to try it out, and then only count the days that they actually USE the program! Makes them feel like they are in control and they can try it out when they have the time (everyone are very busy people, give them some flexibility!)
Sure you can make the trial time shorter. 30 days is a long time if it is spread out over a year... Make it 10 days. My bet is you will get more people buying the program because they got time to use it. I don't want people paying for something they don't really need, especially if it is something I have provided. I want my users to WANT to pay for it because they think it's awesome, not fool them into buying something they dont really need or want. Knock your socks off service. What a concept. Give me some of that!Off you go, implement my brilliant idea and give me credit. Let me know how it works out. :)