I use 1Password 7 and only use a local vault (synced across devices with Resilio Sync). There is no reason you have to pay for a subscription if you don't want to.
It has detected Dropbox sync out-of-the-box and kept working with existing settings. But it won't refill passwords, unless I either subscribe or buy a license (a pop-up forces me to do so). I'm curious why you're not seeing the same behavior.