First, congrats on having a successful company and doing what you love (and employing others - a great feeling to know you are helping technical folks live their dream).
Second, some thoughts.
A. State in your policy that multiple trials are possible but may incur a rest period between activations for a “given company.” Even 5 days should be reasonable for honest folks but cause a pain point for dishonest ones.
B. If you can add a license activation feature to your software, collect metrics when you present the license activation screen, and “bake in” the telemetry to your trial license key request. Things like CPU ID, hard drive serial numbers, TPM quotes, asset tag serial number. Use that telemetry to determine “given company.” The abusers are likely installing this on the same system over and over.
C. Independent of the activation idea, If the trial hard-stops after 30 days, maybe you could delay the approval process on all new trials by X days (X randomly chosen from range 0..5, and all trial requests independent of requestor) and then activate the product for 30-X days. Assuming the dishonests have integrated the VM into their production systems, this will cause an unpredictable unavailability and trigger a pain point somewhere. At worst, it will cause them to step up their request efforts.
As others probably are saying, this might be one for the lawyers.