They would only be entitled to bug fixes if they are still on maintenance with Sage

if the client is running a version of Sage 100 no longer supported then there would no longer be new hotfixes or product updates on that version created or released by Sage.  

Initially, the hotfixes and product updates are still available for download for versions as newer versions are released but once a version becomes unsupported it is only for a limited time updates/hotfixes are available and then they are no longer available for download from the Sage 100 portal (but the partner may have a local copy of fixes or updates for older versions that they can install for clients as needed).  

If hotfixes or product updates are still available on the Sage portal, the client would be able to download these if they have an active support plan for Sage 100.

An active support plan will always allow them to download any hotfixes or product updates for supported Sage 100 versions as well as the full product download for those supported versions (to perform an upgrade).

If they are "on plan" with Sage (meaning: perpetual current on maintenance, or active subscription) they are entitled to upgrades / updates / hotfixes.

For anyone who does not have a current license, we only apply patches / updates / hot-fixes that were released while they had an active license.

Otherwise, we do "best effort" at keeping a customer running, with a caveat that we can't guarantee anything on unsupported versions.  New script or custom report in an ancient version (perpetual, off plan), no problem.  Help with an error message... sure.

(I can't comment on Master Developer type licensing considerations at all).

So there is Sage support without being on subscription? 

Does Sage frown on partners that support customers that are running non-supported versions?

AFAIK: Sage does not provide support to customers not on an active support plan.

We're always encouraged to get customers to upgrade / stay on plan, which we try to do, but the final decision on such things is up to the client.  We even have a few customers who are current, but running older versions... because upgrades come with cost and risk (balanced against the risk of running older software, and missing out on new features).

Kevin,

I guess my question is if a customer has already paid for the software, invested heavily in customization and happy with the support by their partner, does Sage still love them?

The problem I see is if the customer signs up for the 'plan' and then reverts back to their partner for support,  Sage can disable their software to be read only.

If the customer purchased under perpetual licenses, they can continue to use that software for as long as it functions.  Perpetual will not "turn off".  They can't get updates and can't use new software technology with older version; but can hobble along on an old version they purchased via perpetual, after they stop paying annual maintenance.  And a Channel Partner can continue to assist them as needed without installing new updates or any hot fixes available after they stopped paying maintenance.

If the customer purchased under subscription licenses, they can continue to use the software as long as they are current and paying their subscription; like any other vendor offering a subscription.  You stop paying and you stop getting the goods. 

Will the customer or partner be 'punished ' if Sage isn't seeing continued revenue from software that has already been paid for?

I have an opinion on how Sage handled the transition from Perpetual licensing to subscriptions that is not favorable, but Sage has every right to set the terms and conditions of its software subscriptions however they wish.

If anyone violates any licensing agreements, yes.  Otherwise, I can't see why / how.

Should you not be aware, the subscription is enforced by a "dial home" service... it's not an honor system.