It needs to be a Company,
a 'Company' ... 
Why not implant
Your family can throw a treasure-hunt party after you die
what I mean by 'company' is rather the aspect of a company that offers permanent succession and not dependent on any single person being alive or working for them, much in the same way the cyrgenic freezing 'companies' are set up.
It may be a trust, foundation, company, etc...any way that's one of the features of a company I was trying to strike at.