After you compile your app, there is a "show permissions list" button. It will show you all the permissions that are required for your app.
The READ_PHONE_STATE will be there if you are using PhoneId.
Note that the license manager doesn't really require it. You can use a different id.
You can keep this permission and add the uses-feature described above. On tablets without a telephone the call to PhoneId.GetDeviceId will raise an error. You can catch this error.