I worked at a company which made heavy use of a math library that had license enforcement via a method rather like FlexLM. After enough complaining, we got them

I worked at a company which made heavy use of a math library that had license enforcement via a method rather like FlexLM. After enough complaining, we got them to send us an unenforced version -- and they became a little more proactive in sending us annual bills and asking if we needed a new number of licenses. If you're paying bigbucks, try asking for better terms. Explain how painful it is for you, not to pay them, but to not be able to use their software. Maybe it will work.