Google will now limit you to four de-authorizations of Google Play Music each year
Back in 2012, Google had originally placed a limit of four de-authorizations a year. Back then, a public outcry followed Google's announcement, which led to a reversal. This time, it doesn't look like this will be the case. And if you do go over the limit, don't expect a stern warning from Google. Instead of a message, it just won't remove the device you requested.
Even if you don't switch devices often, you could run into the limit. Each time you do a factory reset, Google creates a duplicate device. And Google has been known to accidentally dupe a device for no reason. Perhaps if the crew in Mountain View were to give a reason for the limit, everyone would be more understanding.
If you can get a Google rep on the phone who is having a good day, apparently he can clean out your entire authorized device list in 24 hours, and let you start from the beginning with four de-authorizations to your name. But this seems to be a courtesy that Google will give you once a year, and only if you ask nicely.
source: AndroidPolice via MobileSyrup