I ended up scoring a free lifetime membership years ago, but is their stuff open source? I never fully trusted it, so I didn't end up using it for anything
It's not open source, so that's an easy deal breaker for some. Considering the vaults are encrypted and Enpass itself stores nothing on their servers, I've been okay with it. The vaults just exist on my phone and wherever I've chosen to back it up (OneDrive, GDrive, Nextcloud, NAS, etc).
Enpass uses the open source library sqlcipher (which is an sqlite fork with encryption). So while Enpass as a whole is not fully open source, you can still exfiltrate your passwords with open source tools, should they ever vanish or radically change their business model. You can then use for example enpass-cli.
That gives me enough confidence to trust in Enpass, since they can't easily hold my data hostage.