Freeze candles before you light them (and in between uses) to make them last longer. This works with pillar candles and votives, both in and out of containers. Put the candles in the freezer for a few hours or even overnight. When you take the candles out of the freezer, wipe away the condensation with a paper towel or cloth. The cold air hardens the wax, and that slows down the process of melting.
If you’re really into candles, you might consider making your own. Hand-made candles are gorgeous and make inexpensive yet thoughtful presents. Be sure to tell the recipient about this candle-freezing hack!