I use only free software and when I was offered a lifetime licence for some, I refused, because it it is against my policy. I usually recommend freeware and it would be hard, if I were not using it. I do not mind ads and other restrictions and I would rather donate, then to be "forced" to pay, when there are alternatives. As it was said, free is not free anyway, like when you are using a free AV, you help to improve its detection, report bugs.
Even the dev said, that he does not mind, when people keep using the trial forever, as long as they are using it, because it helps to promote it, so more people will buy it. I like some of its features, like the ability to create SFX archive and unpack it to a custom folder, no other software has it.