These are trial licences so good chance support won't be able to help you with them. Also running F5 BIG-IP in GNS3 isn't support either I expect.
I dont believe there is much to do, the restart probably caused the hardware ID to change, making the licence invalid.
The GNS3 website comments on F5 BIG-IP suggest an approach you could try for a next attempt: "To solve the licensing issue with GNS3 it's best to download the iso and install as a virtual machine. Install the license to the virtual machine then import the vmdk into GNS3."
Hopefully F5 will issue another trial licence.
https://gns3.com/marketplace/appliances/f5-big-ip
You could also look into a lab licence, which is around 100 dollars and comes with support. there you can revoke it and start again, if needed via F5 support.