This article provides a complete, 360-degree breakdown of the Reaper license key—what it is, how to buy it legally, the difference between commercial and discounted licenses, how to install the key file, and why avoiding "cracked" keys is dangerous for your studio.
This is difficult but not impossible. Contact Cockos support with proof of payment (bank statement, PayPal transaction ID, or credit card charge). They are reasonable but cannot always recover keys tied to inaccessible email accounts. Reaper License Key