Buying a Heavy Weapons License allows you to purchase the following items classed as 'Heavy Weapons' in the game by the Federation Security Council:
- Medium Compound Blaster
- Medium Blaster Turret
- Heavy Blaster Turret (subject to Military Approval)
- Quad Light Compound Blaster Turret (also requires 'Protective Technologies License' and subject to Military Approval)
- Thunderhead Lance
The license always stays with you, even if you buy a new ship.
Note: the Exotic Ships and Weapons License subsumes the privileges of all other licenses.