Integrity has always been free (aside from a short experiment). A number of my smaller applications are now free. This is because of changing expectations and I'd rather have a large number of non-paying users than a very small number of paying users.
However, I've dedicated my life to improving what I've done and doing more (yes, as a full-time pursuit). If you're using Integrity and you feel that you'd like to make a contribution, or if you are using the software as part of your business then perhaps the best way to help is to buy a licence for Integrity Plus, Pro or Scrutiny. You can compare features and prices here.
Alternatively / additionally, if you'd like to be the smartest-looking peacock or hen in your office, take a look at the tees and hoodies below - we get a small amount for each one you buy.