You get 2 hours a day with free Siel's Aura. After those hours are up, if you don't have a purchased subscription then you lose out on any items higher than white/common grade as well as any kinah that happens to drop. So once your daily free Aura runs out you will be unable to loot any uncommon, heroic, fabled, or eternal grade items that drop. You also lose the ability to gather items via Aethertapping/Essencetapping while your Aura is greyed out. The subscription cost is now only $10 which is much cheaper than most other subscription based MMORPGs where you're not even able to log into the game without an active subscription.
Here is a link detailing the changes that happened to Siel's Aura and what it now provides/what you get when you don't have it.
Cookie's post in Collecting Kinah doesn't work / unable to obtain items at current time was marked as the answer
