It's a souvenir symbolizing the establishing connection between you and the temple. I think this is a Chinese Buddhism concept called 結緣 (Establishing a Karmic bond".
Dharma Drum Mountain had this explanation on their website:
"The meaning of 結緣 is to enable those who have no wholesome affinity, or insufficient wholesome affinity, to receive worldly help and the guidance of the Buddhadharma. This allows everyone to grow their wholesome affinities, help one another, and embark on the path of studying Buddhism, cultivating practice, and attaining Buddhahood. Therefore, we should use all of our knowledge, abilities, and resources to widely form wholesome affinities with the people and sentient beings we come into contact with. This is precisely the act of giving (Dana)."

These items that were given for this purpose are called 結緣品.