itimpi

If the extended SMART test is failing then the drive should be replaced ASAP.   Even if you have/had cable issues this would not have affected the extended SMART test as that is internal to the drive,
 

Unraid does not split files across drives, so you need to make sure a disk has enough space to contain the vdisk when it grows to its maximum size.   If there is not enough space then the VM will stop working when the drive runs out of free space.
 
another possibility is to bypass this problem by passing a complete physical drive to a VM.
 

Do you have the My Servers plugin installed?  If so you can get your key file via that. 
It would also be included in any local backup you have made of the flash drive.
There is also the possibility you have it attached to an email from Limetech.
 
In the worst case you can email Limetech and they should then be able to help but that may take a bit longer to get resolved.

All drives that are visible to Unraid when starting the array count towards the licence limit.
 
If you are passing a disk controller through to your VM then drives attached to it will not be visible to Unraid and thus not count.  However if you are passing through individual drives (i.e. ones that show up under Unassigned Devices) then they DO count.

Have you restarted the array since making this change?   I believe there is a bug in 6.10.0. Rc2 where such a change will not take effect until the array is next started.
 
note that as long as you have set the Minimum Free Space setting for the cache pool (set by clicking on the pool name on the Main tab) to be larger than the biggest file you intend to copy then even with the Yes setting Unraid will start by-passing the cache when the free space falls below that value.

Unraid will not do that -  you must have configured something to make that happen.   The most likely culprit I can think of is the CA Backup/Restore plug-in being incorrectly configured to point to that location for storing backups.
 
the only way I can think of to recover the data will be to restore it from your backups.T

Seems unlikely that Unraid will be directly vulnerable as it does not use Apache.
 
I guess it is possible that VMs or Docker containers that use Apache could be vulnerable.   Quite what knock on effect this might have if one got compromised is unclear as they run within controlled environments isolated from core Unraid.