Cloud service to check licenses?

Compatible with VB.NET, is there a free cloud service (i.e. no free trial, no credit card) that can be used to check licenses, while maintaining a level of security/privacy (i.e. you can't just look through all names and licenses!)?

I got shot down like a UFO on Stack Exchange for daring to ask for a link to an online service, so maybe you'll appreciate my question better! Here's a list of what I tried but didn't like:

• Mega.co.nz - needs an SDK that works with C# only
• Azure - requires a credit card/MSDN subscription
• Google Drive - not sure how this would work securely - does anyone have any ideas?
• AWS - requires a credit card

I have looked on others, but I haven't come across any that are both secure and free. I know, it's a lot to ask, but I'd be interested to see if there are any solutions.

My ideal solution would work something along the lines of that you visit:

acloudservice.com/myapp/is_a_valid_license?license=1234-5678-...

Which would return a value, e.g. true or false. If the license is valid, it would also contain the license key encrypted with the licensed user. To check the correct person is using the license, you would try to decrypt the encrypted phrase using the given name. If it works, you're licensed.

So really what I need is an online service that lets me contain a database of licenses and lets me write code to accompany it (for the license checking). I could just get a server, but in the absence of that, what is the best cloud service that does this?

Or is this just too much ado about nothing, and could I just use a Google Drive sheet with everything in plaintext and check if the license key and name are correct? What about if someone reverse engineered the program to get the link? Or used a traffic monitor?