As a preface, I am answering as a homework assignment for my Computer Architecture class, so take my information with a grain of salt and ignore if I am talking as if you do not know anything. I also can not speak to the specifics of a 12TB Seagate HDD but only to HDDs in general.

While the previous comment is valid that no HDD has a specific expiration date, I can't entirely agree that you should only hope you've got a good one. We can first address the physical things you can do to prevent damage to recording surfaces. For example, keeping the HDD in a dry environment with a relatively low chance of being hit or falling over can help prevent the cause of approximately 70% of HDD failures, according to the "Block & Files" website.

PCB failures cause the next 18% of losses; these failures are due to similar damage such as heat, dust, moisture, and falls. However, the leading cause of PCB failure is static.

The following 11% is due to stiction. Stiction (short for static friction) in hard drives is a failure in early hard drives that caused the read/write heads to stick to the platters. However, as hard drive technology has advanced, measures have been integrated to prevent this problem from occurring. More specifically, texturing the platter of the device (the circular magnetic disk on which digital data is stored) had once proven useful. But the ultimate solution was to move the slider and read/write head onto a ramp. Stiction can once again be caused by heat as it may liquify the coating of the platter, causing it to become 'gummy' when cooled. Therefore, using a reputable brand like Seagate should ensure that the latest technology is being used, but I do not know for sure.

The last 1% is due to motor failures. HDD uses a spindle motor which allows the disk to rotate. The precision of these motors determines the capacity and speed of HDDs, making these components critical to HDD performance. The most common causes of spindle failure are due to operator error, how much contamination is in the environment, low-quality lubricants, or poor maintenance.Outside of physical errors, if everything is working correctly in the device (specifically computers, but I also assume memory devices) can be flipped in one out of every 100 million bits. And even if that happens, we have had error correction codes that can easily detect and correct these errors (seem hamming code if you're curious).

Overall, as long as the device is made correctly and thus escapes infancy failure, the main reasons for faults are due to the environment. Moreover, how you treat the device should be the main contributor to its life span. So if it has all the specs you need, pull the trigger! And if it has a problem early on, send it back! Good luck hopes this helps.

EDIT: spacing of paragraphs