Upgrades are free, as it has always been. Just needs validation for version 501 and higher (only once, generally a matter of an hour or so, but there was a cue since the first v.5xx release). The validation can only be received from Gunthar personally (no charge for license holders). I believe he wants to make sure only true (or better genuine?) license holders can upgrade to versions 501 and higher. From what I'm reading, there seem to be counterfeit/hacked licences on the market which by this additional validation procedure are denied upgrades.