Hi, Can you confirm the exact version you purchased and where did you buy it from.
Acrobat Reader is a free software, Acrobat DC (sometimes called PRO) is purchased and installed from Adobe Creative Cloud using your username and passwords, not a licence code or serial number anymore.
Other brands sell a software called PDF Reader Pro, but not Adobe. Can't help you there.
If you have an old DVD with a serial number, it is possible that the software is too old and the servers that validate the code is now turned off.
When I log into the adobe account I get this message, I have contacted support via chat. there is another enterprise account linked to the same email address. Because of this the user cannot use adobe reader pro. This is because this license is linked to a user profile. can you not remove the link with the enterprise account, this is already expired anyway. [cid:image001.png@01D87CC9.6DE0A820]