Some years ago, I bought a perpetual license for FlashBuilder 4.7. Recently, it failed to build an Air package because the product, which hasn't been updated for years, connects to an obsolete time server. To fix the problem, I followed the directions in Adobe's support site. Right after doing this, it asked me to re-enter my license key. It rejected it, saying it was no longer valid. A license that was sold as perpetual, no longer valid!

Their support was completely worthless: after being redirected to five different support teams that had no clue how to solve my issue, I realized I was never going to get a solution, and gave up.

My personal lesson learned: never buy or use anything from Adobe ever again.