Basically, you should always adhere to all valid agreements with streaming providers, which could prohibit recording. If you break agreements, the provider could, for example, block you.
But there is also a question of personal data protection: Which data traces does a streaming recording potentially leave behind with the provider?
So the following considerations deal with the data a streaming service provider could see while you are recording.
In general, it looks technically "the same" for a streaming service, whether you are only listening or watching, or recording - it does not "notice" the recording at first.
A recorder like Audials can behave completely passively, leaving no traces.
However, Audials offers some features that make recording more convenient. These lead to the fact that certain "data traces" can arise with the streaming provider:
Music recording: “remote control” mode
Audials offers two modes for some streaming software.
The "Drag music from XYZ to Audials" mode controls the streaming software remotely in order to play the desired music. This creates a certain "pattern" (all songs are played individually), which could be detected.
The alternative mode “play music in XYZ”, on the other hand, is completely passive, here only you control the streaming software. There is therefore no data pattern when recording, which deviates from the "only hearing” use case.
Music recording: speed
For some streaming software, Audials offers the practical "high speed" option to "let time pass faster". (How fast this goes depends on the streaming provider, which must also enable this).
This could also be measured by the streaming provider, even if it probably is not very easy to distinguish this from buffering cases that also occur with normal listening.
When recording at “normal speed” (1x), these data traces do not appear.
So far, we are only aware of a few individual cases that suggest that streaming providers have evaluated personal user behavior in order to detect streaming recordings and then addressed the users.