When you sell a company there are two major methods. A complete sale of assets (which it sounds like you did) and a sale of stock (which is preferrable).
the sale of stock would guaranty you long term capital gains.
I'd say that you should be taking a capital gain on everything generally
But, intangibles like copyright are funny. The creator can sell the copyright and sell it, but when you sell it theres a problem. How do you determine the basis of the copyright. Generally, companies buy copyrights and etc so its easy for them to have an adjusted basis or cost for them to calculate. But, you developed and created the copyright so your basis is probably going to be pretty small and the gain is going to be HUGE. You can say that you're hours spent is an increase in basis. Same rules apply to songwriters and etc.
You can sell the IP, but the gain is going to be significant.