The lifespan of a pillow-top mattress really depends on the construction and materials of the mattress itself.
Maintenance for a pillow-top mattress includes vacuuming the mattress on a regular basis to get rid of any dust mites, debris, or skin flakes that may accumulate. Some mattresses with pillow tops do actually contain a cushioned layer on both sides. If that’s the case for yours, flipping the mattress every three or four months can also extend its lifespan. Usually, you should not flip a pillow-top mattress, though.
Once the mattress begins to lose its shape, sag, or develop tears in the fabric, it may be time to start shopping for a replacement.