Except the pro option is not "a few years later" it's available in pre-v1 and is a one-time lifetime purchase, not a subscription.
And the framework and docs are so small and simple, that you can read the entire site in an hour or two, in which time you would have noticed the pro features and pricing many times.
At the risk of repeating myself, I was talking in general terms about the business model and the uncertainty about the licensing it creates concerning possible future features.
I wasn't aware that they are a non-profit organization and agree that my remark doesn't necessarily apply to them since they're not a business. If the pro subscription helps them to maintain the open source project without making any profits, then that seems alright to me.