Adobe Illustrator is no longe available in my plan

Arthur, in addition to Kglad's suggestion, you can use the steps listed in https://helpx.adobe.com/enterprise/kb/enterprise-id-faq.html to verify you are logging in under the individual Creative Cloud All app plan that is active under your account. The behavior in your post does look like you are logged in under a restricted Creative Cloud account.

If you are trying to access a membership managed by an organization or educational institution, let Monika, Kglad, and I know. Our solutions may not be effective for a Creative Cloud for Enterprise or Team membership.

it that plan is administered by the school, check with your admin to make sure they didn't change anything.

otherwise:

1. sign out of the cc desktop app (http://helpx.adobe.com/creative-cloud/kb/sign-in-out-creative-cloud-desktop-app.html)

2. delete your temp files

2a. win: open settings > system > storage > temporary files > delete files

2b. mac: - open finder > go to menu > library (use option key if not seen) > application support > adobe > common folder > delete media cache and media cache folders

3. if that fails follow https://helpx.adobe.com/in/enterprise/kb/resolve-trial-and-license-expired-errors.html#sa_src=web-messaging

info from https://community.adobe.com/t5/creative-cloud-desktop-discussions/i-m-locked-out-of-most-of-my-apps-even-though-i-have-a-creative-cloud-all-apps-plan/td-p/14022283

This is the Illustrator forum. We can help you with Illustrator issues. There have been a couple of questions like this lately. I have asked for this to be moved. 

@Jeff_A_Wright  can you help, please?