Software Registration Process

One solution is to use TDownloadUrl action (in ExtActns unit) and make your php script return somekind of ini-file so you can easily have additional information, witch you can
show to your user. Actual response should be crypted someway.

  fDownload := TDownLoadURL.Create(self);
  try
    fDownload.Filename := 'C:\Temp\Result.ini';
    fDownload.URL := 'http://myserver.com/myscript.php?code=1234567890';
    fDownload.ExecuteTarget(nil);
    ParseResultIni('C:\Temp\Result.ini');
  finally
    FreeAndNil(fDownload);
  end;

Your software is time limited, hopefully you have considered what if user turns computer clock back?

Ok

First you need an serial number encryption system that allows you to encode not only the user's serial number but also the fact that it is time limited.

Have a database table with customers name, serial number, date allocated, current time limit and encrypted registration string (If issued).

You could issue software with a tempory activation key as standard.

The software when run for the first time checks the registry for a valid registration, as none has yet been entered, a registration key is requested. A default Registration key with 30 day timer is entered.

Once the user has entered this, then the encrypted data can be stored in several points within the registry, along with the encrypted installation or issue date. The format of the encrypted acivation key should be modified prior to storeage in case the user tries to find it with a registry search using the activation key you supplied
Example:
Date encrypted as StrDate
procedure TfrmRegistration.InsertDateInstalled(strDate: string);
var Reg: TRegistry;
begin
    Reg:= TRegistry.Create;
    try
        Reg.RootKey:= HKEY_CURRENT_USER;
        if Reg.Openkey('<AnyFolderName>', true) then
            Reg.WriteString('<dateIssued>', strDate);
    finally
        Reg.CloseKey;
        Reg.Free;
    end;
end;

Thereafter when the software is run, a number of different routines from various points within your software should extract the data from the registry and decrypt it, Only the decryption routine should be in your supplied software).
Then run calc against current date to see if software authorisation has expired. If the software is out of time then set a number of booleans to flag the fact and take some sort of action.  Set another registry value to record that the software has expired. This registry reading should be checked ever time the software is run and acted upon.

To help prevent the user from resetting the date encrypt within the registry the number of times
that the software has been run should also be encrypted and stored in the registry, if the number of runs is checked and if it exceeds a preset number then action can again be taken.

Increment the number of times the software has been run after each check and re encrypt the result.

The Activation code needs to look different for every new serial number that you issue, so that certain
characteristics such as the time limit or lack of time limit are not identifiable,
otherwise this may allow the user to change part of their serial number to affect the time limit.

Having embedded a time limit, you can either prefix it with an encrypted marker to indicate its start point or place it at a fixed point, although the latter is not adviseable.

ie Variable length dummy prefix + Serial no xxx + Time Limit or No Limit + dummy suffix to pad string out

Below are two simple examples with a key code run up for this example only.

Dummy prefix variable Length + Serial Number 1234567890 + Time Limit 30+ Dummy suffix
NERK94wV9|5/Djd1X8KnALOJ-ejpEBelza0uXYz@tyoXKX8GbGUg0I2AQcG.YSGkLN:npMC/QrhcMSUE41@4W

Then the same serial and time limit with slightly different prefix to give an entirely
different activation key string

Another prefix of variable Length + Serial Number 1234567890 + Time Limit  30+ different suffix
:0Dwn:F5g4IEaETZ9uYmxtHECBsQYqQ.21bzgNLdTQbsboSliCz1hWbWvhSO:TG3LNLTBavcquipjtU4P1@lHX2oNpXPa|0

The two encrypted strings contain the same base information but look entirely different.

When the user runs the software the registry details should be  looked up from a number of different points within your application and action taken according to the results returned.

Good luck