If I can share my personal opinion on this topic I think it can not harm any one to have a symbolic 1€ per month (10€/Year) Subscription with extremely few additional features. I’m near sure that a lot of people would take it.
Myself who currently do NOT make any cents on my platforms (Despite some of them have complex project with crazy architectures) I already though give away 30€/40€ (could even be 75€, it’s not the amount the problem) but never I planned to buy a professional license (Then maybe I’m not the best example and I only represent a minority in this community).
According to me the biggest feature of the pro plan is the Professional premium support. This feature is undoubtedly, from far, the Most important, the one you should highlight and really worst 75€ per Year (And the reseller account, even if it probably target only few members). But all the other, when you are a pro, you can setup it yourself.
Then I also repeat what I said in this topic Virtualmin 'Testing Mode" for the complete newbie - #22 by Tactikast
The 10€ per year subscription could be perfect for Prebuilt Configuration (What the current ‘first time setup’ try to do):
• Mail Only
• Static Website Only
• Mega HUB (DB, SQL, PHP, Cron Job, mail ….)
With everything ready to run ( Maybe a prebuild index.php ) and no additional setup to do (at least for the 2 First). A kind of educational First Step, Ludic/Playful Example.
Then I might be wrong.