Wiktionary
come in handy
vb. (context idiomatic English) To be useful or helpful, especially at some time in the future.
WordNet
come in handy
v. be useful for a certain purpose
Usage examples of "come in handy".
I'm beginning to think a little witchcraft can come in handy at times.
But I might mention something that might come in handy, maybe not.
It'll also read vital signs, which will come in handy for evaluating a subject's state of mind during scan.