Upgrading from Artist to Professional

Here's the situation: I just paid for the first moth of my Artist membership ($4.99 per month). I don't need the additional content or plugins that the higher levels offer. But then I realized that Elastic Audio is not included in Artist.
 
So, now, I'd like to upgrade to Professional. My question is: if I buy the Professional subscription, will the automatic payments for Artist be stopped? Do I have to cancel the first membership before I start the second? Will Cakewalk automatically bill me for only the higher membership?
 
Thanks in advance for any info.