First of all, Akeeba Release System will manage the downloading and releasing of your plugins.
You will need to create a user group and a view access level for each plugin file (an item of Akeeba Rlease System), where downloading this plugin file is allowed only for users with the corresponding user group and view access.
On the other side, Akeeba subscriptions will manage the payments and subscriptions, you will create a subscription level for each plugin, each subscription level has 2 actions:
- Add to Joomla! user groups: Users will be added to these Joomla! user groups when their subscription to this level is enabled.
Remove from Joomla! user groups: Users will be removed from these Joomla! user groups when their subscription to this level is disabled.
The level is enabled when a user finalizes the payment for it, and disabled when it is expired or cancelled for any reason.
So, Akeeba Subscriptions will handle adding/removing users to Joomla user groups, and Joomla user groups are having view access, also Akeeba release items/files are controlled by view access, so only users having a valid subscription will be able to access and download the plugin they paid for.
I didn't play with Akeeba Tickets System, but I think it will integrate with Akeeba Subscriptions through the view access.