I have a few incentives from different products. Some of them I don't ever think I will sell and others I'm not so attached to. The ones I felt I would never move I have cracked and put into magnetic cases. The ones I am not attached to I have simply put into a team bag so that the case doesn't get scratched.
Ultimately, if this is for you and is something you won't sell, take the card out. If you think you'll move them at some point, leave them in.
Another thing you can do (and I have done this in the case of the few I have removed) is to peel the sticker back carefully, take the card out, put the sticker back in place and store the loader with the sticker in a place you can find it. If and when you feel like you need to sell it, you can put the card back into the holder.