Minecraft Launcher Issue for Java

What I expected to happen was...: When I bought the Minecraft Java Edition from the Minecraft Launcher, I had to transfer my data to a new computer since mine was getting old and I bought Java edition and I wanted to play when I got a chance

What actually happened was...: When I went back to the launcher ** to play Java on ** my new computer, it said I had to buy it even though I already did and now I have to buy it again for $30. I don't know why it did that