I don't know whether it's legally possible to decay equity. Equity is seen as property, so once it's granted you can't just revoke it. You can expire or revoke

I don't know whether it's legally possible to decay equity. Equity is seen as property, so once it's granted you can't just revoke it. You can expire or revoke options, but options themselves don't grant any right other than buying or selling the underlying asset. You could do something like a maturing bond, where it grants payout rights, but that doesn't give equity. You can just plan on a constant level of dilution, ala Bitcoin, but that doesn't ever actually remove previous ownership.