I still have the serial number for this specific version which is the 2015-16. But I can only find the one for 2017-18 and 2018-19. I remember registering and I'm sure that it should still be valid until January 2019. I changed to a new PC now and I can't re-install it since I already uninstall it from my previous PC and I just can't find the installer anywhere. What should I do?