Lifetime of MC43FS

We have a project that is to be used for the next 40 years. It is a functional safety system that utilises MC43FS. These modules will likely be superseded multiple times (probably due to enhancements in electronics etc) after the 20 years lifetime shown in the manual:

To guarantee functional safety, presumably its recommended we remove and replace the MC43FS after 20 years as described in the manual regardless if the module is working correctly? I'm trying to avoid re-assessing the system in 20 years time and fitting a safety controller available in 2045. Therefore I intend on having a brand new MC43FS available for when the system needs a replacement module in 2045.

Is the 20 years triggered as soon as the module is powered up, therefore we would need to clone the software only when we want to replace the module in 2045 (rather than installing software now and starting the 20 years timer)? Or has the module 20 years been triggered from manufacturing date on the serial number?