Hello,
I'm an expert in VBA and VB.NET with almost 10 years of experience. I have written a similar dll in the past already. You can call this dll with one single line of code and it will give a true or false value back.
I can add extra parameters so you can specify the amount of days the trial should last, and a unique identifier you can use in the license key. I will also add a second program you can use to create the license key, based on this unique key.
The license key will be encrypted and will also have a time stamp, so the key will only be valid for a short period of time.
Will you just need the dll or do you also need the source code. If you would also need the source code, I will have to add 20$ to my bid.
If you want more details, just send me a message.
Best regards
Wesley