Recently, I have installed two software tools that were supposed to be free, but politely told me that my demo period has expired, offering me an option to pay. If they were advertised as trial software, I wouldn't have considered them at first, because I usually want to make sure that the installed software will work without future problems. Free versions have worked for me so far. But I suspect that the high popularity of free might slowly be becoming the trojan horse into people's PCs, trying to bind them to commercial solutions. Advertising trial software as free is (for me, at least) effectively hiding the truth, where the main goal of software developers should have been to be honest with their users.
The problem isn't only wrong user expectations, but the fact that a system can be left in a dysfunctional or unstable condition, possibly without the user even noticing it. In my case I had an antivirus and email programs that effectively stopped working, but stayed there as if they were working. If the software has expired, why do you allow me to still interact with it? Isn't there a way to close it and not allow to be opened again? If I haven't noticed that the antivirus has stopped working, I would have gathered one or another virus. I needed to send myself test emails just to check if what the email software was telling me was real, because there was no indication on the main screen that something was wrong. The message of expiration appeared once in a small popup that I simply closed.
It's best that the software doesn't leave people clueless about what it is currently doing. Constant feedback (in addition to honesty) is one of the most valuable things from a user's perspective.