So Raise has a couple of different ways that they sell cards. One of them is as a reseller. If I buy a card from another individual at a discount I just buy it right before I plan on using it and use it right away. I'd never hang on to a card from them.
In addition to that though, they also have partnerships with some companies where they sell new gift cards and instead of giving a discount, they give you a credit back towards your next purchase. This allows you to buy a card for the exact amount you need and it's a new gift card. I still use them right away but it's also probably a bit safer. I just buy a $1000 card, copy and paste the number into Carnival and then use my $80 towards the next card until my amount is paid off. I've done it now for 2 cruises with zero problems.