Wanna upgrade my Pro 16 to 19 Post. On time payment. Still can't find any info whether I can use Pro 19 (Post) on my PC and laptop simultaneously like I can with my Pro 16. Is the Pro 19 Post license working for 2 machines?
If by "on time payment" you mean the 365 (subscription), please note that it may still be different, i.e. one device at a time. For Pre-sales consultation email infoservice@magix.net. Of course you may mean one time payment, then set's advice is correct.
Regarding VP 19, please note that currently the option to deactivate the software from the Help menu is not available in VEGAS Pro 19. Hopefully this option will be back in an early update.
You can still deactivate a device (so you can activate a different one) on your MAGIX account > My Products > Show More Details > Deactivate. This option can be used only once a month AFAIK.