A shower head should last between 5 to 10 years and sometimes longer.
Most times a shower head just needs cleaned because calcium deposits build up in the shower head and cause a loss of water pressure.
When you notice that your shower head is not spraying water out properly then the shower head is likely becoming clogged with some calcium deposits from the water.
Overtime those calcium deposits build up in the shower head and restrict the water flow.
You can usually clean the calcium deposits out of the shower head by filling a Ziploc bag with some vinegar and then tie the Ziploc bag with vinegar around the shower head and let the shower head soak in the bag of vinegar for 1 to 2 hours.
The vinegar will break down the calcium deposits in the shower head.
Then run the shower with straight hot water to flush it out.
If the shower head has become fully clogged then you may need to replace it with a new one.
I usually replace my shower heads after 10 years which is quite a long time.