Converting a paid service to a free service

Are there any examples where converting a paid service to a free service caused issues for subscribers?

Imagine a startup with a paid service, that is acquired by a large corp who lacks a subscription model for consumer services / products.

I hope this is a useful scenario, but either way, my core question is about the ramifications (e.g. perception of value, etc) of converting a paid service to a free service.

I don't imagine an angry client complaining when he doesn't have to pay anymore.
It should be important to ensure the users/clients that the change doesn't mean that the project is going to be terminated. Nor that the support will be reduced and so one. If the quality remains and the service become cheaper/free I can't imagine any negative impact (with the exception of some exclusive or luxurious services that people buy to "be different", to "show it's not for everybody" or to "show they can afford it")

On the contrary, this kind of change can be well exploited by the marketing : e.g. if the service will in be in a portfolio of services, just tell to the clients that they are important for the company so they will be offered a free service now... and in the meantime, they can check the other proposed (paid) services (so they can spend the money they save by the service that become free).

One important thing: it would be very bad idea to come back to the paid scheme later again. That would surely be damageable for the company image and the trust between the company and its clients.