Is subscribing the only way to get that cover? I preordered via Previews and specified that I wanted all covers.
You don’t have to subscribe to the whole series to get Sarah’s cover for issue 1 (you should subscribe to the whole series, because it’s awesome, but you don’t have to).
A ‘subscription cover’ just means you had to pre-order it, instead of just picking it up off the shelf the day it comes out. Now, you might not get Llivio’s cover because that’s a 1 in 10 retailer incentive, so it’s up to your retailer who (if anyone) gets that cover — unless you ordered 10, in which case, thanks!