After 90 days, the switch enters a "licensing grace period". Features continue to work for another 60 days but will syslog warnings. For perpetual lab use, you will need a Cisco DNA Virtual Subscription (low-cost academic/DEVNET options exist).
qemu-system-x86_64 -machine pc -cpu host -m 8192 -smp 2 \ -drive file=cat9kv-prd-17.12.01prd9.qcow2,if=virtio \ -netdev user,id=net0 -device virtio-net-pci,netdev=net0 \ -nographic -serial mon:stdio