Yes and no.

I haven't seen a cheque in my whole life. Just heard about them 😆

How long can you cash in a cheque? How long can you redeem your zaps?

You have them, they are yours. You hold the only key to use them, and I don't think that it matters if you use them. I'm sure in some countries the possibility to redeem is also enough to make a taxable event out of it.

Don't get me wrong, I love your work and I'm amazed by the speed you are coming up with new stuff.