I can't speak to the legal options available and I am not a lawyer, but if there is a beneficiary you can put in your will/trust that you trust with access to G

I can't speak to the legal options available and I am not a lawyer, but if there is a beneficiary you can put in your will/trust that you trust with access to Github, then you could put a couple copies of a keypass database, or even a text file on a couple of USB sticks and put them in a safety deposit box for someone to inherit. I would assume they have power of attorney. Perhaps you can make an agreement with them to periodically push a commit to a README.md file. This assumes you are not making payments to Github. If so, the executor / beneficiary in your will or trust would have to take over making payments. If that is not an option, then maybe the account will stay active if you make them contributors to your project. I don't know if Github will keep a project live if at least one contributor allowed read-write access is active. Everything I am suggesting may violate some AUP/ToS, but I have never been one to let such things get in the way when no other options make themselves available. On a side note, something I do with VPS providers is to prepay them extra so that I have credit in my account. Even if I stop paying them, my services will stay live for years, if for no other reason than to have cron jobs email people I know so that my morbid bad humor can live on for some time. Perhaps you could do something similar so that your book continues to make money for your estate? Maybe another option would be to find a site that specializes in hosting static content specifically for this purpose and put in redirects on github to that site.