Is it okay to compress application files? (Especially licensed applications) I have attempted to research this but given the fact that applications exist to compress other files, I've found it difficult to learn about compressing applications themselves.

I presume its okay to compress applications in general – they are like any other file.

However, before compressing applications which require licenses (for example pre CC Adobe suite), I want to make sure the license will continue if I compress the application and delete the uncompressed file.

If I compress an application and delete the original will I lose my license?
(I understand this could be different for different applications; is there a generic answer?
Most macOS applications are not actually like 'any other file' - they just look like one - and are actually a folder of files called a package. Right-click on most apps, and you will see a Show Package Contents command. Click that to see the folder structure of the app. 

That being said, applications will compress and expand just fine. I've compressed and expanded Adobe apps with no effect on licensing so long as they are expanded onto the same system.

Compressing an application and expanding it on a different system may break licensing if the licensing mechanism itself resides outside the app's package, or if some other licensing scheme is in effect. There is no generic licensing scheme for all circumstances.