When you write an article or something for a magazine, they sometimes give you an oiption to get paid in save-ups. Save-ups are bits of paper with the save-up amount written on them. The save-ups can be used when you are subscribing or renewing your subscription. The save-ups have a certain value. For example, 4 Sirius save-ups is equal to 1 issue of Sirius. So, if you are renewing your subscription for 10 issues, you need to send 40 save-ups.
Save-ups are better than money, because even if the magazine price goes up, the save-ups will still have the same value compared to the magazine. And if the magazine price comes down, then you don't need to use the save-ups - you can pay using money and save the save-ups for a time when the prices are high.
Save-ups were invented by the CATS magazine. Nowadays, it is only used by Sirius. Aldebaran has a similar thing called Stardust, but you can't use it for subscribing. Instead, you can use it to buy some special items in the Callisto website, which can only be purchased using Stardust.