When you pay for goods or services, you should expect to receive something. If you pay extra for leather seats, you’re getting leather seats. If you pay for DLC as part of a game, you’re subsidising the cost of the developer adding more stuff to the game. The pricing of digital products and add-ons may not always be fair but you should be getting access to something valuable that you didn’t already have, i.e. something that costs money to develop and/or host.

In this case, you already bought and paid for the additional RAM. The manufacturer is refusing to let you use it until you pay additional money, even though you theoretically own it already. That’s not providing a service, it’s just extortion.

If you could somehow prove that the additional RAM was not factored into the original cost of what you bought then this might be fair (albeit wasteful) - but I doubt it…