Even though this is a case where one benefits and the other does not lose? The viewing itself does not harm them.
Granted, I should notify them, but until then?

Stealing in order to return it is also forbidden. There too the owner suffers no loss. True, some have held that this is only rabbinically forbidden.
But here it is not even in order to return. In my article on intellectual property I wrote that taking information is forbidden as theft, and I explained that information has value only if it is unique, so anyone who takes it damages the value of the information.

So that means that halakhically, the very use of someone else’s property, even though it is with his knowledge, is forbidden?
Because I notified them, and it still was not canceled.

And what about cracked apps on Telegram, like Spotify?

I do not understand what is unclear here. If someone leaves the door of his house open, are you allowed to go in and take his things? They left the door open and you go in and take things from there without permission. If you want to watch — please pay.
Telegram—even if you pay, it is forbidden to use it. It is a gathering place for thieves.

There is no comparison. In the example you gave, that is outright theft; in my case it does not deprive them of anything. In addition, I notified them that the subscription was not canceled and they did nothing about it, so maybe it is their responsibility.

What about watching movies on Telegram? Seemingly the prohibition is on the distribution; my viewing material that has already been distributed no longer steals anything. Is that permitted—especially since it is already like property swept away by the sea, the owner is aware of the distribution of the material, which is what happens with all movies today. Is that permitted?
Thank you very much for your time.

Michi, more than 20 years ago (when you were more Haredi or less secular or somewhere between religious and Haredi—pick however you want to define yourself, because the public is confused), you gave a lecture in Bnei Brak and made an entire pilpul that this is forbidden under the prohibition of deception, and you wanted to rely on some Ritva for that.

David, I answered everything. The claim of “property swept away by the sea” is not relevant here, because this is not use of the same item.
Each viewing is something different. Just because he already ate garlic, should he go back and eat more…?

What a Loss, indeed. I do not think there was a Ritva there. I referred here to my article on intellectual property, and there I explain it.