The RiekerTEX membrane is basically very robust and durable. If cared for correctly, the shoe will maintain these excellent properties for its entire life.
Dry shoes gently, do not leave close to a heat source (e.g. heating, oven): the material can crack if exposed to high temperature fluctuations.
Take a break from wearing your shoes to allow the trapped moisture in the material to dry out.
When impregnating the shoes, make sure that the spray is suitable for TEX membrane materials.