Hi there! So glad to have you joining us!
Carrie is absolutely right. As long as the kit is by a current designer, you can use it. It doesn't matter where you got it, if it's retired or no longer available, if it was a freebie, etc. So, you're welcome to use anything that you have by Flergs!
If you have any other questions, just let us know! I've changed your forum permissions, so you should be able to jump in and make yourself comfortable now!