After getting a licence correctly from Licence Server, the licence is not free at Licence Server level when clicking on release licence button but Neoload has no more licence. By this the licence is blocked at Licence Server level and Neoload have no licence. We have to wait the licence expiration date to be able to use is again.
This occurs on Neoload 4.2.1, Licence Server 3.0.3. Remark the licence management working well with Neoload 4.2.2.