Lab License $99

LAB License is valid for all versions of BIGIP later than v11. The service check date is set to the day you licensed it. In order to upgrade to a version of BIGIP which has a "release date" later than the service check date you need to renew the license which costs nothing. However to renew the license you need a support agreement with F5. This is why there are ongoing costs with a lab license as you have to pay a small amount each year to maintain a support agreement. When you bought the license it should have been paired with a support contract or at least recommended.

If I were you I would just call support, say you want to move to a new bigip with the license. They can release it from the existing hardware profile so you can re-use it as it is a permanent license after all. Note they may or may not do this without a support agreement. I am not clear if it's required.