Atwork has three kinds of people. Members work in your workspace and take a paid seat. Guests open a view, page or form you have published, without an account. Portal users are your customers, who sign in to your portal to see their own records. Only members cost money.
| Member | Guest | Portal user | |
|---|---|---|---|
| Who they are | Your colleagues | Anyone with a published link | Your customers |
| How they get in | Added by the owner in Users | A link you have published, with Guest access set to Yes | Create Portal Access on their contact, or self-registration |
| Signs in? | Yes | No | Yes, at your portal |
| What they see | The spaces and sheets they have access to | Only what you published | Their own records, plus what you publish with Customer access |
| Takes a seat? | Yes | No | No |
| Managed in | Administration → Users | The item's Publish dialog | Administration → Customers |
Members are your colleagues. They sign in, work in your spaces and take a paid seat each. The owner is a member too and takes a seat.
A guest is anyone who opens something you have published with Guest access set to Yes. Guests have no account and take no seat.

Portal users are your customers. They sign in at your portal and never enter your workspace.
See What is the client portal? and Portal users and access.
No. Only members take a seat. A five-person agency with forty clients on its portal pays for five seats.
Only if you allow it. Guests get the role set under App is when you publish. Keep it on Viewer for read-only sharing.
No. A portal user sees their own records, plus anything you have published to all customers or to their segment.
Delete their row in Administration → Users. Atwork asks you to pick a replacement person, and everything the member created is assigned to them. The seat is freed.
Open the Publish dialog, set Guest access to No and click Save changes, or click Unpublish.
Related: Roles and permissions · Seats: adding and removing people · What is the client portal? · Share a view · Pricing