I don't know if they expire in JP but I'm really sad that they expire in NA. Does anyone else have opinions on this?
Normally I like to buy premium currency in bulk and then sit on it for a long time until something nice comes along in a premium shop. This saves the added headache at the end of a stressful work day if I want to get a nice digital thing but have to think less rationally about what's appropriate to spend on a video game. If I already have premium currency there, then less-stressed rational me already decided that it was appropriate. I do this with all games that I play (League of Legends, Path of Exile, Mabinogi/Vindictus).
I'm much less likely to buy and sit on lots of SG because of the threat that it'll expire out from under me before I notice. It's meaningless gouging to have SG expire like this.
[EDIT] It seems like SEGA currencies expire because of tax issues in Japan. AC expires in JP, I can't find any info on whether SG expires in JP. It's odd that this appears flipped in NA. Does our AC expire too???