Is flexsearch index persistent?

[pedrovgs]

I'm trying to find a full-text search library I can use for a pet project I have, and I'd like to know if this library supports persistence and if so, what storage is used under the hood. Reading the documentation I can find some paragraphs about storage like this one and others about exporting/importing data but I'm not sure if this library is using any persistent index or you have to load the index manually and maintain an in-memory version.