You might also need to check whether the IAM part of the key has expired. Sometimes the API Management feature has a different expiry date to the rest of the Licence.

I got caught by that last month.

I'd love to know how this turns out. Don't forget to post if you get anywhere!

Also, maybe let everyone know what platform you're running on, and is it real hardware or virtual?

Well they fixed an OpenVMS bug in 2017.1.3, so it's still under some support. InterSystems usually say that anything older than two years (4 years for security corrections) is on 'best effort' basis. Which is usually pretty damn good - I had a question about Cache 5 last year and they were great.

Cache 2017.1.3.319.6 is listed on the Online Distribution page for both Alpha and Itanium.

OpenVMS was discontinued for Cache 2017.2 though, so 2017.1.3 is your last version. That should get you up to 2022 anyway.