Activate on other iOS device with different Apple ID

Hi,

I am a happy pianoteq user. I used it on PC, Raspberry Pi and tried it on my wife's iPad (using her Apple ID). Now I bought an iPhone just for using Pianoteq (and similar apps). But I can not activate pianoteq for my Apple ID. The error message says "the serial number is already linked to another Apple id". I already deactivated it from the "slots", and also uninstalled it from my wife's iPad.

I also contacted support. But if it's something that I can somehow solve by myself, it will be interesting for others to find it in the forums.

Thanks