BYOL means Bring Your Own License. It is a licensing model where a customer reuses an existing software license in a different environment, such as moving a workload from on-premises infrastructure to a cloud or virtualization platform. The goal is portability: the software remains licensed, even if the hardware or hosting model changes.
In cyber security, BYOL matters because licensing can affect resilience. If a vendor changes BYOL rules, blocks transfers, or tightens validation, organizations may lose the ability to rebuild systems quickly during migration, recovery, or incident response. Defenders use BYOL to preserve continuity and reduce downtime, while attackers can benefit indirectly when rigid licensing slows patching, scaling, or failover. For that reason, license terms are part of operational security, not just procurement.