Hi Steffi! They are similar to a salve in stick form, so will stay fresh at least 9 months to a year. (Often much longer.)
They don’t really go bad (as far as mold or spoiling, or anything like that) – instead the oil ingredient will eventually age and turn rancid & the sticks will develop an ‘old oil’ smell.
Even then, you could still technically use them, but they just won’t smell that great on your skin.
You can help the oils stay fresh longer by adding a few drops of Vitamin E or rosemary extract.
Store in a comfortably cool spot, out of direct sunlight, to help them age slower too.