I have purchased several websites from my aunt and I opened an Adsense account (my first one). Most of the sites are already transferred and have ads running. There is only one site left to be transferred, which is currently still on aunt's account, registered as the primary URL with which she applied to Adsense years ago.
My question is, does she have to close her account having in mind that there will be no other sites for now on her account and her primary site will be under my control? Or can she just leave her account open in case she has other sites in the future?