The project uses MD5 Encryption to generate the serial key, specific to Machine. The Unique key on system basis is generated and respective serial key is verified with the MD5 Checksum. Can be used on Flex / AIR products selling.
Also, uses SharedObject to store the unique System Key
var reg:MD5 = new MD5();
reg.registereduser – > status of user registration
reg.skey – > serial key of the end user
reg.setRegKey(reg.skey); – > to enable the product
Note: The project is 3 years older work done by me.