@dusty.lau Magix should have send you a serial for SpectraLayers Pro 8. If you cannot find it please contact sales support at infoservice@magix.net or shop@magix.net.
Since SpectraLayers is now a Steinberg product I don't think Magix is responsible for issuing licences for the latest version. My understanding (and I may well be wrong) is that all existing user data was transferred to Steinberg when they purchased the software and so they are responsible for issuing the missing licence.
However, as @SP. says, there is certainly a good reason to contact infoservice@magix.net and ask them.