Hi Clarence,
1. Any Advice in the Upgrading PowerServer to 2019?
Please test PowerServer 2019 extensively before updating your production server.
You may want to wait until PowerServer 2019 Developer (PB Edition) is available in June of this year so you can also update your Developer Edition of PowerServer and have all your PowerServers running the same 2019 version.
2. Is there any instruction document how to do the Upgrade?
Here's the full documentation on the installation of PowerServer 2019: https://www.appeon.com/support/documents/appeon_online_help/ps2019/installation_guide/ar01.html
You may want to start on this section: https://www.appeon.com/support/documents/appeon_online_help/ps2019/installation_guide/ch03s03.html
3. Is it an upgrade or I have to uninstalled the old version and install the new version?
If you plan on continuing to use your existing production server, then you can install PowerServer 2019 on top of PowerServer 2017. No need to uninstall PowerServer 2017.
4. What a bout the licence. Would I have an issue with it?
If your organization has kept up with its maintenance payments (USP - Upgrade Subscription Plan), then you have the right to update to any future release of PowerServer at no extra cost. If you are unsure if your organization is within USP, please contact sales@appeon.com. If you are within USP, the sales team can help instruct you on how to activate your PowerServer 2019 with a perpetual license file.
5. Do I have to pay again for the 2019 PowerServer Version?
Not if you are within USP, as described above, if your organization has kept up with its maintenance payments (USP - Upgrade Subscription Plan), then you have the right to update to any future release of PowerServer at no extra cost. If you are unsure if your organization is within USP, please contact sales@appeon.com
Cordially
Mariano C.