Why are we limited to the number of auto unit hiders when purchasing with soulstones? We earned them, you made the item why can't we keep using soulstones, they just pile up.

Hi! You can buy only one Item of that kind (it doesn't matter if you buy it for Sapphires or Soulstones). And the duration doesn't matter as well. Once you have at least 1 Item active or stored at the Black Market, you will be unable to buy another one.