You do not get any type of certificate, but HDTracks et al do keep records of your purchases. The best thing to do, as @ibmjunkman suggests, is to have backups. I have local and cloud backups of my music library. This is also more easily accomplished with a NAS.
I think you're right about the Venus 12th being the platform for Pontus 15th - that value proposition was one of the reasons I jumped on it. So glad I did!

