You don't need to worry about the major version of DynaPDF. Major upgrades are included in the maintenance. No, nothing will change for you when the major version will be increased.
In most software packages, the major version is more or less increased every year or every two years. In a final application this is of course important since the customer should buy regular updates. To increase the major version, new features must be programmed on "stockpile". For a PDF library that needs to be constantly maintained and expanded to include additional features, this is rather counter-productive.
The major version of DynaPDF was increased just three times in the last 10 years. New features will be added when they are needed. It is not required to increase the major version every time new features will be added.
The major version must be increased when changes on the API must be made. However, backward compatibility has the highest priority in DynaPDF. Therefore, the API will only be changed if other ways would cause too many disadvantages. This is very seldom the case.
The minor version is incremented every time new features are added. A version like 126.96.36.199, for example, provides the information that 25 times one or more new functions were added. On the basis of the major and minor version, you can check whether the loaded DLL API version contains the features you need.
The build number will be increased with every update. BTW - The DynaPDF version can be queried with GetDynaPDFVersion().