I paid in 2014 for Logic Pro X 10.0.6 (forced to buy a new copy when my 2012 Logic Pro 9 wasn't allowed on newer versions of MacOS). I have the receipt etc. However, when I try to install from App Store with the same account as the receipt, it only shows $199.99 Buy Now, with no option to install. Constantly trying to force me to buy again. I found a solution!