Are you suggesting that the purchased product is some kind of "canned" Access-based application?
In essence, you need to know the same sort of things you would need to know about buying a car with a product warranty. Software can break in numerous ways. Know what is covered and what isn't. You need to determine the level of support you get from your provider.
The standard questions will be "length of software warranty" (90 days? 1 year? Renewable support contract?) and "response time to errors" and a clear definition of what constitutes product misuse or abuse to a level that would void any warranty. Specific questions would have to include "support rights in light of published Microsoft patches that have the result of disabling the product." (It can happen!) Determine if the product has been sold with the idea that it will be maintained by the supplier or whether you implicitly take over maintenance the moment you buy it. (i.e. implies the need to hire a support person.)
One important factor is whether you were provided with a "user's guide." Another is a "maintenance guide" - particularly if you are in the "user provides maintenance" situation. You need to carefully delineate what is YOUR responsibility vs. what is the provider's responsibility, spelled out in careful terms. This is going to sound Draconian, but if your company has the means to do this, you should investigate your state's law on mercantibility, i.e. determining whether a product is suitable to be publicly sold.
