How do you choose the length of your product free Trial? Many webapps offers a 30 Days free trial, while some offer a 7/15 days Free trial, is there any "Right" lenght here? how do you do it?
It depends partly on what your app does.<p>If it is a tool to add special effects to a photo, a 7 day trial might be plenty. If it is an app to measure SEO effect on we traffic, the user is going to need a longer sample time.<p>I do not think there is a universal right answer. You want it to be long enough that the user gets a proper feel for the value of the product, and short enough that they are pushed to make a buying decision while it still feels new and exciting.
At what point is the app most useful, i.e when does it become meaningful for the user?<p>It doesn't HAVE to be in days does it?<p>Look at Dropbox, their free tier lasts for however long it takes you to fill up 2.2Gb, 'cause once you get to that level a) you know it works well b) you're using it regularly so upgrading is barely an issue because you've already seen the worth.<p>If it's a photo app you could say 50 images, they have a certain level of investment into the app so it becomes useful.<p>If it's a game, when does it become addictive? level 3? 50,000 points? 40 in-game hours?<p>I think users find 'use' in apps at different rates. By cutting them off after x days - you essentially lose them. Let them carry on under a certain threshold until it becomes meaningful to them, they'll upgrade to a paid plan.<p>Let them mature to the point where they are most likely to upgrade.
My advice: your trial should be a minimalist version of your product with an unlimited duration. When a user signs up for the trial, add them to your mailing list. Then, when you add features 1 month, 3 months, 6 months from now, you can mail your users about them, and that user can log back into his trial account to try it out.