Activation query

Hi

I have a computer which dual boots Windows 7 64-bit and Linux
I have Pianoteq Std, registered on the Windows system.
I would like to have it also on the Linux system
I've tried the demo version in the Linux system, it works fine.

Does this count as one installation or two, for licensing purposes?
I guess it depends if the activation code takes account of hardware and O/S or just hardware.