Best answer is quoting from the Deezer Support knowledge base:

With the Deezer Free, Deezer Student, Deezer Premium, Deezer Duo and Deezer HiFi plans, you can connect up to three different devices. However, you can only play music on one device at a time.

With Deezer Family, you can connect and manage up to 13 different devices linked with six profiles. This means family users can listen and play music on up to six devices simultaneously.

For further information, please refer to the relevant article: Connect And Remove A Device.

Hi @ChairSpud !

From Deezer Help center

With Deezer Premium and Deezer Student, you can link up to three devices to your account. It's important to note that you can only play music on one of the three devices at any one time. These subscription offers are designed for individual users, not multiple users or families.

Tip: If you're interested in a plan that accommodates multiple users, see our Deezer Family offer

Thank you for your reply. Yes I’ve read this in the deezer FAQ but have also read the more complete deezer Terms and Conditions which clearly state the 3 device limitation applies only to when downloading the recordings and listening to them offline.

Per deezer Terms and Conditions:

Unlimited access, on up to three authorized devices (personal computers or mobile devices) for the purpose of temporarily downloading the Recordings, in order to then listen to them when offline.

My experience during trial of the Premum plan bears out the ability to live stream one stream at a time to one of more than 3 devices. Only when I attempted downloading did the 3 device limitation occur.

So what’s the story?

So ,if I understand you quite well , you want to say that you was link up more then three devices to your account and in same time you was able to play music on more than three devices at the same time !?

Only live stream to one device at a time but to any of six devices.

Why so complicated?
With Premium you can only stream on one device. If you start the stream on another device, playback on the first device stops immediately with a message.
In principle, you can pair 3 devices with the account. The web version and desktop app are not counted.

I think not all devices count towards the limit.

For example, my phone I installed the Android app on does count, but my PC I listen to music from via the web browser does not, it is not connected on my Deezer account.

Just now played deezer one stream at a time on four different mobile devices a mix of android phones and ipads with no restrictions.

Well, that's wonderful. Deezer promises 3 devices, you can use 4 devices. Don't think about it, just listen to music.

On deezer trial considering subscribing annually and do not want to discover surprise limitations later on with a non-refundable deezer subscription.

I suspect the deezer FAQ on the subject of streaming only may be incorrect and contradicts the deezer Terms and Conditions. Does anyone here have personal experience to the contrary with streaming deezer music only?