Ensuring you have the final updates (up to version ) installed.
Adobe no longer issues patches for vulnerabilities. Using this version makes your computer a prime target for PDF-based exploits.
Check the back of the CD/DVD jewel case or the sticker on the sleeve of your original installation disc.
If you purchased a volume license, you can Retrieve Serial Numbers by signing in with your Adobe ID.
Reports from security experts and software communities highlight several dangers when looking for keys or "activators" on repositories like GitHub: Malware & Trojans