If you just bought it a month ago, you should be within the one month grace period, and should see something to that extent when you log into your MySteinberg portal. I’m not sure what the GUI looks like in there but it should be visible that you have Grace Period Eligibility. I believe the cutoff date was March 27 or 28 or something like that, so as long as it was after that.
Yeah, sorry, but this does happen, they have to have a cut-off date somewhere in time.
It will be discounted at some time in the future if you want to wait (or maybe it is possible to download the trial version to evaluate?)