Firstly, I think it is helpful to regard IP as an asset ( in the same way you would, Business Goodwill or a business itself, for example ). And, as far as I can see, this regard is the thesis of this article.

Viewed from this perspective, all the standard methodologies used in valuing a company can thus be applied to value IP: Income Approach; Replacement Cost; Market Comparability Method…. to name but a few.

Like asset amortisation/depreciation, different methods can yield vastly different values. In that vein, like business valuation, IP valuation is more a symbolic, I would caution, than a substantive approach to establishing true value.