I just cancelled my stock trial. Excellent service, btw. Can I still access the library?

If you go to https://stock.adobe.com/Dashboard/LicenseHistory, you can see your licensed assets and can redownload them, as long as they don't get removed from the database. I suggest you keep a local copy save on your disk, however. And I further suggest that you make a screencopy of your licence list and safeguard that too. It will be your only proof that you have correctly licensed the assets.

I do not know how much space the assets take in your library, but the free Adobe account comes with some free cloud space. I suppose that will be enough to store your assets, even if you do not have an Adobe subscription.

You may access your libraries with the following link: https://assets.adobe.com/libraries