I check at the Akeeba support and don't see anything that helps with this problem:

I have a website where anyone can view items and articles (real estate properties), but must be registered to contact property listings etc
K2 is the content system.
If a registered user wants to post properties, then they must subscribe at some subscription level that is setup with Akeeba Subscriptions.
A subscription thru Akeeba is setup to add the user to the Joomla groups REGISTERED and SUBSCRIBERS. This works as it should when they subscribe at any level.
However, I have the K2 users setup to only be able to post articles if they are in the K2 SUBSCRIBERS group. The problem is that Akeeba does not change the K2 user to the SUBSCRIBER group. So even tho they have paid there subscription, they are not able to post unless I manually change them in K2. Even if they are in the Joomla SUBSCRIBER group they are not put in the K2 SUBSCRIBER group.
What am I missing?

Hi,

You are not missing anything. There is no integration between Akeeba Subscriptions and K2 user groups. You have two options here:

1. Create a plugin that will update the K2 user group automatically.

2. Ignore K2 user groups and just go with the native Joomla! user groups. You can set the SUBSCRIBERS user group to be able to use the administration area ( not the front-end ) and give them access only to K2.

Thanks Lefteris. That is not going to work. I do not want any access to the admin area for anyone. The 2 groups need to have different access levels to the same content. it seems that with K2 it is all or nothing
I will look at the RsJoomla Membership or Subscriptions for K2 and see if they will do what I need. I am not knowledgeable enough to create a plugin.