BerkeleyDB was distributed with the "Sleepycat License" since 1996 which is similar to GPL in terms of permissiveness so it's not like BerkeleyDB has been distributed with a permissive license in the past. If the Sleepycat License suits your needs but for some reason AGPL doesn't, why don't you just take the last Sleepycat-licensed version and keep using that? It still does everything it did when it was released. People could even fork it and make improvements to it.