How long do Telemetry Parameters stay in the configuration

Arnold Harding - KQ6DI

When Telemetry Parameters are received from as station such as EQNS, they go into the configuration file. 
How long will the parameters remain there assuming they aren't refreshed?
One of my stations only sends EQNS once a day, but I noticed APRSISCE/32 already had the equation stored.
Arnold, KQ6DI

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