Can I upgrade HueForge for less? Or do I have to pay twice?
Absolutely you may upgrade your version of HueForge.
Do this by adding the tier you want in the shopping cart, then apply one of three coupons:
PUUPGRADE - use this if you currently have Personal Use
LCUPGRADE - use this if you currently have Limited Commercial
PROUPGRADE - use this if you currently have Professional.
Each coupon code can be used once, so you could upgrade from Personal Use->Limited Commmercial
Then Limited Commercial->Professional
Then Professional->Lifetime Professional.
However if you upgrade to Limited Commercial, you cannot then use PUUPGRADE again for your annual re-enrollment. Or against any other upgrade. And the LCUPGRADE and PROUPGRADE coupons are good for the period during your upgrade.
Upgrading from Limited Commercial->Professional restarts the clock on your year.