[dragonwriter]

> Per-copy licensing, which is the base of most commercial software distribution, is pretty much impossible with the GPL.

Equivalent basis for support contracts, which have actually been the key part for many years in most non-consumer software contracts even when they nominally include copyright licenses, are quite possible (and common) with GPL software.

[_ph_]

When you are selling a support contract, GPL is no problem. But this does not cover the sale of a software which costs many thousands per seat, you cannot make up lost sales revenue with support contracts. The cost pressure would drive customers to use the software with way more seats than they have support contracts for. And the GPL would prevent any legal licensing scheme which would try to enforce a support contract per user of the software. There are exceptions to this - a hosted platform like github can of course count the number of accounts created for invoicing.