Purchasing more buildings

I'm at level 30 and whenever I try to purchase something, especially anything royal,
I get a message that I need to level up. But I think level 30 is max since I've been
at that level for a long time.
I completed the Explorer's Badge and the Knight's Hall but unable to purchase.
Yet I noticed the experience points keep accummulating. Does anyone know the
answer to this?
Thanks

You have reached the limit for royal items. You will need to sell a royal item to be able to build more.

Thanks kooky panda. So I work hard to build something and I now need to sell it?
Does that go for non royal building as well?
Do you know if there are plans to add additional levels to this game or will it die just like the Hidden Object game?