Only looking at lifetime value delivered ignores the competition, much of which is free and easy to switch to.
Also support costs typically go down over time; most support effort is spent in onboarding and getting users up and running. Although now that you mention it, Evernote may have huge technical drag because they have bugs outstanding from over six years ago. Indeed, the only time I reached out to support (I couldn't install PC version because it was incorrectly detecting that I already had it installed) they weren't able to assist. $10 lifetime value may be a bit generous.
Also support costs typically go down over time; most support effort is spent in onboarding and getting users up and running. Although now that you mention it, Evernote may have huge technical drag because they have bugs outstanding from over six years ago. Indeed, the only time I reached out to support (I couldn't install PC version because it was incorrectly detecting that I already had it installed) they weren't able to assist. $10 lifetime value may be a bit generous.