Regardless of whether you invested in a top end or budget-priced PFD, it behooves you to treat it right so it can do its job on your behalf.
Always hang your PFD up to dry after use. Leaving it to molder in your car trunk will encourage mildew and other infestations that can actually deteriorate the fabric and the thread used in the PFD. This will increase the chance that the PFD may fail while in use.
Do not leave the PFD at the bottom of a heavy load of gear as this can lead to a permanent reduction in the thickness and hence the buoyancy of the foam. If foam is left under constant compression, the cells of the foam will take a permanent “set” in the compressed condition and not offer the same flotation capability it once had.
Basically, treat your PFD with respect. Don’t leave it in a damp boat or musty basement or laying out on the deck where the sun can get to it. Don’t use it to pad your canoe while in storage. When you think about it there’s a lot riding on being sure your PFD can perform up to standards and expectations.