I think the B4i License is Forever. But you only Renew for Upgrades (when available)
Example: If you pay for STANDARD license (2 Months of free Upgrades), and B4i IDE is updated within those 2 months from v10 to v11,v12,13. You will get All and use.
But if that 2 months passed, you can still use the IDE with your license, but you will be stuck on that last version you downloaded. So if NO NEW Upgrades to the IDE after that, you are good to go, But if there is upgrade then, you have to renew