I understand that basic functionality is for free, but I saw somewhere research showing that apps that allow one to try out without login at all (providing that

I understand that basic functionality is for free, but I saw somewhere research showing that apps that allow one to try out without login at all (providing that the actions are made on the client side of course, i.e. not writing anything to server-side data store) attract more clients than the "must-login-before-try" approach