Have a look at this: ByteArrayBuilder - a StringBuilder for Bytes
] - it's what I use to do that: it lets me build up an array of bytes from the standard datatypes and then I save it to disk. When I read the file back, I can "undo" the array back to the standard datatypes very easily.
And it's pretty easy to add encryption to the byte array so your licence data is harder to read...
BTW: It's a bad idea to use a hardcoded folder, and especially one hanging off the root of a specific drive - and when that is normally the boot drive it's a very poor idea. What happens if my boot drive is read only?
Instead, consider keeping your data is a more appropriate place: Where should I store my data?
] - that way teh system will keep track of it for you and you won't have problems.