Google looks as though they have once again imposed limits on device deauthorizations when it comes to Google Play Music. These device deauthorizations were also in place two years or so back before they were removed after a while. Under the Play Music settings page as well as in Google’s support docs, either one would inform users that they are able to deauthorize a quartet of devices each year.
Basically, if one were to go over that particular limit, the user would be greeted by a message that reads, “Sorry, you’ve deauthorized too many devices.” When you are greeted by that particular message, then chances are you will have to wait even for up to a year, before you will be able to continue to remove devices from your account and prevent them from being counted as part of your 10 device limit.
Assuming you have maxed out on both limits, on paper, you are more or less prevented from streaming Play Music on other kinds of mobile devices. This particular change would mean one will have to be all the more careful in considering the number of devices that you intend to authorize, as well as how one “spends” the quartet of free deauthorizations every calendar year.