What' s the life span of power surge protections?

I owned a couple of nice Panamax surge protections for about eight to ten years now. Is it time to replace them ? How long do these things last? All the functions appear normal. Thanks for your inputs.
Service life is determined by the type of transient absorbers used in your protector, and their electrical environment. Most cost-effective designs incorporate metal oxide varistor transorbs, which are sacrificial by design and therefor will degrade if hit repeatedly by large voltage surges, and can even occasionally be blown to smithereens by a single catastrophic event.

Most household applications typically operate in benign environment, so chances are that your Panamax is fine although there's no guarantee of course. If your location experiences significant lightning events that disturb your commercial power, then your transorbs might have degraded over the years.
I believe that Panamax, as well as several other manufacturer's protection PLC's will actually shut off their power output if the internal transient protection feature is not functioning correctly.
The Panamax surge protections are so delicated and so sensitive. Sometimes, it turned off the connected equipments even though other equipments and lightning equipments in my household still on while I heard some thunders/ lightning far away. Still I need to know HOW OFTEN do I need to purchase a new surge protector? Please have me advised.
I expect my Brickwall to last forever. There are no MOV's.
No surge protector will help if lightning strikes between the power-pole transformer and the power lines running to your house.

Surge protectors work for voltage anomalies, but WILL NOT PROTECT EQUIPMENT FROM A LIGHNING STRIKE!!! Unplug [don't just throw the circuit breaker] your gear if there is electrical storm activity in your area!
Good point, Mt10425. You did check one a while to make sure your brickwall not cracking up, didn't you? Foundation repairs could be expensive.
Look towards the warranty as a guide. Panamax, and others, offer lifetime warranties, which could imply that it need not be replaced. But be careful, the warranty could specify a voltage spike limit or duration in milliseconds, which could mean that even a new unit may not protect you in some circumstances.

What impact does repeated overvoltages have over the course of years? The best way to answer your question is to contact Panamax and see if they still back it up. I doubt they'll steer you to an unecessary purchase.