If you need specific historical versions (like 3.0.5.1 or 3.0.5.3), these repositories are commonly used:

: Hosts several older versions, including DroidVPN 3.0.5.3. APKMirror : Offers version 3.0.5.3 (156) as a secure mirror.

: Standard free accounts are limited to 200MB of data per day and are restricted to specific free servers.