If you have AnyConnect 4 Licenses for your ASA 5505, then you can use these also with your next ASA. All other licenses only apply to the 5505 and you have to look for corresponding licenses on the 5506. But the feature-sets are not the same. Where for example on the 5505 a Security-Plus license was nearly always needed, it's often not needed on the 5506 as many of the 5505-restrictions don't apply.
