Yes, you can export all your content as a .muse bundle — which you can rename to a .zip and unzip to get all the source data.

Also, even after your subscription ends, you will still have access to your content (and to the export feature) indefinitely. You just can’t create new cards (as long as you have more than 100).

It’s really important to us that your data isn’t locked into Muse, not by the data format and not by a subscription requirement.