Compression stockings don't last forever. (Another reason to get them on prescription.) I think NHS patients are expected to make them last 3-4 months of daily wear - but I guess most NHS patients wearing compression stockings don't run very far in them.
By the way, shouldn't we be having this discussion on the Compression Socks, Compression Clothing or Calf Compression Socks/Sleeves thread? The moderators seem to have missed this proliferation of threads on the one topic - it could benefit by being streamlined into one IMO.