You can use Creative Commons. You’ll still have the copyright to the work, so you can relicense it or do whatever you like with it, but they’ll have a particular and proscribed set of things they are guaranteed to be able to do with it into perpetuity.
Choose whichever license suits what you’d like to be able to grant them, in terms of whether they have to credit you for it, whether they’re allowed to modify it, and so on. CC BY lets them do whatever they want, as long as they credit you, which is a common permissive option.
You can use Creative Commons. You’ll still have the copyright to the work, so you can relicense it or do whatever you like with it, but they’ll have a particular and proscribed set of things they are guaranteed to be able to do with it into perpetuity.
Choose whichever license suits what you’d like to be able to grant them, in terms of whether they have to credit you for it, whether they’re allowed to modify it, and so on. CC BY lets them do whatever they want, as long as they credit you, which is a common permissive option.