The Fantasy Premier League rules do not include details on what happens to unused chips after a season ends.
The wildcard chip available from the start of the season until December is useful when several players are injured or out of action. Additionally, participants can use the chip in the first or second half of the season.
While playing either the Wildcard or the Free Hit chip, any saved free transfers are lost. One can use one free transfer the following game week. There is no clear indication from Fantasy Premier League if points are added to one's final score at the end of the season.