Read out old win 10 key?

I have an old hdd from my laptop and have a new ssd in there on the old one was still a win10 on it can you save the data or the kay?

Yes gitb tools where you have to specify the Windows folder as the target

think http://www.nirsoft.net/utils/product_cd_key_viewer.html has something like that. But there are certainly others

So then folder from the old disk, yes?

I haven't done it in a long time. Believe Windows \ System32 \ Config you have to choose.
maybe it works differently on new UEFI systems if e.g. An OEM key is stored in the UEFI

Ok because with the data rescue system I would have to find it, too, or

Yes, ShowKeyPlus 1.0.7060 is another program. It can read from the currently running OS or you have to specify the path of the offline OS.

https://www.imagenetz.de/D2niG

unless there's a digital license with win10