Is registration required?
vDos is freeware for most. It will however check if the PC is joined to a domain, or files on a network drive are accessed. Then the About popup is displayed every three hours of continuous use. So vDos is also commercial software for business users. A registration or donation would of course still be appreciated if the popup/nag doesn’t apply.
What will it bring?
That nag won't popup anymore. You would contribute to rewarding the countless hours invested in vDos, further development and support, keep vDos freeware for most? You'll be informed of new versions. Some two weeks after the initial release, so eventually reported bugs will be fixed. Registered users however generally don't care about new versions. The current one obviously does the job… I could be more open to your specific issues or wishes, and supply an intermediate pre-release to address those.
What about new versions?
Registration is lifetime and valid for any new versions. If I would decide to change this policy, it won’t affect existing registrations. This is of course no sound business model, while licensing vDos will even die out in time. vDos is however mostly a paid for hobby, so I can commit myself supporting it. As long Windows supports 32-bit applications on x86/64 based PC’s, vDos should just continue to work. Future support shouldn't even be required. To be real safe, a 64-bit version will be available for registered users with the next (2020) release.
How to register?
After filling out the registration form and creditcard payment, you’ll receive an email with the license file and an invoice. The license file is to be copied to the vDos directory. That’s it, no activation procedure or online validation are involved. Transferring a registered vDos to other/new systems still remains a mere copy of some files (plus one).
vDos can be registered in two flavours, they only differ in what vDos eventually validates:
Username: € 50.
The Windows username has to be that defined in the license file. You can opt for more than one, though the price is per username.

Network: € 250.
Unlimited users, as long the PC’s are joined to the registered domain or that network drive is addressed.

The required username(s) or network ID are shown in the nag, the vDos window System Menu - About, or issuing the ABOUT command at the vDos/DOS command prompt.
Money back guarantee?
No, you can (should) evaluate vDos for as long you need to be confident it fulfills your requirements. Once issued vDos licenses can’t be revoked (nor expire) since there is no online validation.