I personally have no problem using commercial software, but my password manager is one place where I suspect that I should be moving to open source in case I don't want to renew my license over some future pricing disagreement, and I lose access to some of my critically important property (passwords).
It's tempting to think that we'll be able to keep our currently purchased standalone licenses in perpetuity, but I've already been dragged through at least one major version upgrade of 1Password to keep pace with new OS developments (for OS X and iOS). There were no new features that I needed or even wanted, but I paid the $50 (or whatever it was, I notice a new license is now $64.99!) anyway to maintain compatibility.
Unfortunately, the landscape for open source alternatives doesn't seem particularly good. Some of those mentioned here like Keepass [1] look like they're usable, but are quite a far shot from 1Password's quality.