Custom server controls that use control state must call the RegisterRequiresControlState on each request during before the state is persisted. Registration for control state is not carried over from request to request during a postback. Use the UnregisterRequiresControlState method to ensure that control state is not persisted for controls that no longer need to be persisted for postback.
Internally, the UnregisterRequiresControlState method is invoked when using the RemovedControl method to remove a control from a controls collection.
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)