Even items that are removed are visible in the downloads page (allbeit greyed out) and you can still get the p/code for these even when they have been removed.
If it’s a very old theme I would strongly suggest backing up where you are at before you make any upgrades
My downloads page shows my three most recent theme downloads, but there is no grayed out item for the one I’m looking for.
The theme creator Kaptinlin, is still providing updates to Striking, It’s just that WordPress won’t let me do an update without the original purchase key.