Multiple activation keys

Multiple activation keys
Hi, I am sort of a newbie here, so I would really appreciate some kind of opinions regarding the flash project I am about to build.

The rules are as follows:
1) When user loads the project for the first time, they will be asked to enter an activation code.
2) That particular activation code will be expired after a month.
3) After that, the user will be asked to get another activation key. The users are allowed to go online to do so.

Any ideas on how to develop this? Normally software asked for the activation key when the user installs, but in addition to that, now I need the users to key in new activation keys every month after the software expires. Thanks in advance.

In my opinion you are in the wrong forum because this is not directly connected to the installer.

But here some hints...
Firstly you should find out how "good" your protection should be (what is the chance that someone want to crack it) and what features it should support(copy protection, what happens when the user changes the date,...)

A simply solution would be a combination of a pool of id's (alphanum) combined with an expire date..
Combinde the id and some validation part (checksum of the id) with the expire Date (for example in the unix date format...)
Then encrypt it with AES, Blowfish or whatever else your System supports..
The encrypted string as hexcode ist your activation key..

In your programm decode the key and check the expire date and the if the id is valid.
Also you should save the key (encrypted) and check if is still valid(expired) every time you start the app or some other timeinterval...

This is not a particular clever method of copyprotection
but it should give you a starting point to develope a better one :-)