Recently a client decided to migrate from Cloud to On-premise. We applied a signed license key (the same as used on Cloud); after assigning the licenses (professional), the following error appears 'you have no access pass'. We tried with analizer license too on published apps, but nothing seems to work.
You say they've moved on-prem and have a signed key. Are they on windows or Kubernetes? Apologies if this seems like a basic question, but does the new Qlik Sense enterprise environment have internet access? The use of signed keys requires this but it is often disabled in on-prem server deployments.