Hi Stanly,
As far as virtual contexts whatever is applied to the main context for licensing is shared across the sub contexts. However some licenses will need to be allocated to sub contexts such as Anyconnect. If you have a 500 user license you will need to allocate how many licenses from that pool can be used in each context.
class gold
limit-resource Mac-addresses 10000
limit-resource Conns 15.0%
limit-resource rate Conns 1000
limit-resource rate Inspects 500
limit-resource Hosts 9000
limit-resource ASDM 5
limit-resource SSH 5
limit-resource rate Syslogs 5000
limit-resource Xlates 36000
limit-resource Routes 5000
limit-resource VPN Other 10
limit-resource VPN Burst Other 5
limit-resource VPN AnyConnect 2
the last one specifies how many anyconnect licenses you are assigning to this class, this class "gold" would then need to be assigned to the sub context.For example if your context name was "Cisco" you would go to that context and add "member gold".
In general licenses are based of serial number so the only reason you would need a different licenses is if you had different devices.
That brings us to the second part. Your active/standby would need the same encryption license on both devices because the second device will have a different serial number you will need a separate platform license.For Anyconnect there is a way to share your license between multiple devices in your CCO license portal.If you need help distributing an Anyconnect license between devices please feel free to contact Cisco TAC. You can also refer to this guide on licensing under the "Licensing for failover" section.
https://www.cisco.com/c/en/us/td/docs/security/asa/asa95/configuration/general/asa-95-general-config/ha-failover.pdf
Also I wanted to make you aware that if you are using failover in multi context with Anyconnect there are many unsupported features.Please take a look at this link:https://bst.cloudapps.cisco.com/bugsearch/bug/CSCuw19758/?reffering_site=dumpcr
Please let me know if this answered your question or if you had any other questions.
