BC = Backwards compatibleYou can get a plus subscription for $5/mo. Less than that if you wait for the year pass to go on sale. You're missing out over peanuts.
Here: https://camelcamelcamel.com/Sony-Plus-Month-Subscription-3000133/product/B00FNQUN7Q?context=search
Also, what does "BC" mean in this context?