My thought on subscription services:
Don't ever do anything to intentionally make your product less useful, especially when there are open source implementations of the same concept or competing products in the same space.
Why would you do this?
If your product can do something at lower subscription tiers, it should do those things. If the problem is that you can't afford to offer lower subscription tiers... don't offer lower subscription tiers.
Your lowest subscription tier is how people are going to evaluate both the character of your company, and the functionality of the product itself.
Your users are smarter than you're giving them credit for, and they'll be able to spot when you're disabling core functionality, or panhandling with add-ons or hidden subscription services that should already be covered.
Don't do those things.
There are other ways to earn subscription revenue.
It's a mistake to do it at the cost of customer loyalty.