A couple of comments from me.
It was actually announced and explained (to a certain extent) here:
You talk about Open Source software, but Blynk isn’t Open Source. The libraries are, but the server-side and app code isn’t.
As far as requiring a PRO subscription for commercial use this makes sense because of the access that gives you to permissions and organisations, but I agree that any degree of testing/showcasing is virtually impossible without biting the bullet and going for a PRO subscription.
For me, the biggest issues lie with the way that new PLUS subscriptions are virtually crippled by the datastream and widget restrictions that have been imposed for new subscriptions, and the way that device permissions are handled for PLUS users.
These restrictions create a situation where Blynk is effectively useless for the average “maker” who wants to give some family members access to devices.
Personally, I’m immune from all of this because I get a free PRO subscription in return for being a forum regular, but I feel the pain from regular users who are happy to pay a sensible monthly subscription in exchange for the type of functionality that give family members access to control home automation devices.
If I was a PLUS user in that situation then I would have found an alternative platform by now. I guess that these changes are intended to prevent commercial users from using the PLUS subscription for commercial projects, but it kills the usability of the product from a maker perspective.
Pete.