does not accept serial number

[Kadir Kesici]

When we enter the 18-digit serial number after the payment, we get an error.

[Reymund Oyong]

Greetings @Kadir Kesici

Thank you for reaching out through our Community Forums!

The activation issue will likely occur if the version of the license does not match the version of the application that you would like to activate. 
Please check the version of your serial number using our license portal (link below):

https://licenses.gonitro.com/prd/portal 

From the license portal, kindly take note of the version. Furthermore, the Nitro PDF Pro installed on the computer must match this version.

To check which version is installed on the computer, open Nitro PDF Pro then navigate to the Help tab > About Nitro Pro. 
If the version does not match the license's version, please uninstall and then install the appropriate Nitro PDF Pro version. 

The Nitro PDF Pro installer (versions 13 and 14) can be located from the link below:
https://www.gonitro.com/product-details/downloads 

Kind regards, 

[Kadir Kesici]

Installing nitro pro 13 fixed it, thanks a lot