"Entitlements" is similar to "licensing" and refers to your authority to access this product.
Once the product has been launched, it is possible to sign out and leave the program open. At this point, any studies that are open can still be accessed; you can modify anything you want in any open study, but you can't create new meshes, run any analyses or open existing, but unopened, studies.
If you do want to open an existing study, you will be presented with the Autodesk - Sign In dialog and will have to sign in to your Autodesk Account again.
If you close the dialog without signing in, you will be reminded that you need to be signed in.
Similarly, if you try to mesh a model, and close the Autodesk - Sign In dialog without signing in, you will be reminded that you need to be signed in to mesh the model:
Unless you are signed in, the Analyze in Cloud button will be disabled.