Licensed users can transfer their Spectrasonics software. Check forums like KVR Marketplace, Gearspace (formerly Gearslutz), or Reddit's r/AudioProductionDeals for legitimate second-hand licenses. You can often find Stylus RMX for $150-200.
Let me be brutally honest about what you're actually downloading when you search for a "WORKING 100%" keygen for Stylus RMX 1.5, 1.7, or 1.9.5: Licensed users can transfer their Spectrasonics software