In Bitcoin mining, we need to have lifetime profits as price goes up and up little by little all the time.
In the long term perspective, 1 Bitcoin can be $1.000.000.
Even if all Bitcoins will be mined by 2200 we still keep Bitcoin blockchain running as we need Bitcoin transfers.
That's tricky, isn't it?
Complicated long technical story. So if you have a lifetime contract your children and grandchildren will inherit it.