Treatment of perpetual license expenses

I’m not sure. Intangible assets is still following the same method of accounting treatment related to finite and indefinite intangible assets.

Finite assets= Amortised for their useful life

Indefinite life assets= Cash will be generated perpetually, it will NOT be amortised, instead, it will be tested for impairment annually. If there is impairment, the reduction will be credited to the asset, while, when there is a revaluation gain, the gain is recognised in profit and loss. 

Intangible assets like licenses are never depreciated.