I tried to upgrade to Plus, but it wouldn't let me. It kept saying I needed to reauthenticate my account. But every time I entered the password to my google/phone account it said it was wrong. I know for a fact I entered the correct password. I even logged out and back in to my gmail to confirm it. I also verified the password in my phone's stored passwords. Nothing I tried worked. It never did let me upgrade to Plus. But nothing wrong with my google play store account. That works fine.