Good luck! Depending on your setup, you might need to migrate stuff out of the /Applications/MAMP folder (definitely back that sucker up before you delete it). I'm back up and running with MAMP Pro 4.5 at this point, so looks like everything worked out. I was able to successfully downgrade by doing the following:
I had to downgrade, as well though in my case it's because mySQL will not upgrade my databases, but I was able to license it.
