I've had to peel off and reuse one my fermometers multiple times when switching between FVs, and that one seems to have endured the stress fine. The bane of these things is excessive moisture from what I've read on here.
However, I question how accurate the readings are since I assume they display the average of the air temp and FV temp combined as opposed to the temp of the fermenting wort itself, which as I understand can vary considerably from ambient temps. I will continue to use them to gauge a close estimate, but for a more precise measurement I'll probably be looking for other options.