You will have to be extremely cautious when discussing about your rights on the digital goods that you are using. Sometimes you own your assets, but in some other cases, you do not really own them. For example, you may not own an ebook the same way you own a hardcover, paper-based, physical book — or music they same way you have CDs at home. If we take the example of the Mac App Store, we might see in the Terms of purchase (which of course you had carefully and thoughtfully read) that you buy a license to use, not a good that you own — and the public realized this after an outburst of actor Bruce Willis.
Some other services, like trusts, can be used to transfer the license to a .. trust. That’s what, for example, a Digital Asset Protection Trust# “can manage these assets and allow those who you pre select to access them without violations of the license terms and without potential liability to others”.
We’re of course not advising you to try to break the law, but you can make it easier for your beneficiaries to access the files that you once “had”. With a proper planning, you can make sure they will have all the cards in hands to receive what you wanted them to have. But having access is different from having the rights to listen to your former favorite songs!.