Will plug-in still work after upgrade?

Hi! So I have a really old version of Calibre. Never dared to upgrade, being afraid that plug-in DeDRM (version 6.5.5 by Apprentice Elf) I once installed will not work in never version. I use it for the DRM of library books. I like to download a lot of them every now and then, and my ereader gives errors once the 3 weeks borrowing date had expired. Anybody who can tell me if it is possible to upgrade?