Just change the First, note that Subversion has no concept of projects.
The repository just stores a versioned directory tree — you may consider certain sub-trees to be projects, but Subversion doesn't treat them differently from any other sub-tree.
When using Apache, it is likely that Apache itself will be the biggest factor in memory usage.
Instead, it is Subversion's repository interface, which is a "versioned filesystem" in the sense that it stores a directory tree whose state is remembered from revision to revision.
Writing programs to access the repository is similar to writing programs that use other filesystem APIs.
Apache, Apache Subversion, and the Apache feather logo are trademarks of The Apache Software Foundation.
Subversion and the Apache Subversion logo are registered trademarks of The Apache Software Foundation. Several companies (Collab Net, WANdisco, Visual SVN, elego, ...) pay or have payed the salaries of some full-time developers, but the software carries an Apache License which is fully compliant with the Debian Free Software Guidelines.
In other words, you are free to download, modify, and redistribute Subversion as you please; no permission from any company or any person is required. It is mature software, with strong compatibility guarantees.