The maximum e-liquid capacity for disposable vapes is 2ml – this usually equates to around 600 puffs per device.
Nicotine containing products which exceed this amount – especially those which claim to offer thousands of puffs – are most likely non-compliant and should not be sold in the UK.
Further, the maximum nicotine concentration for vaping products in the UK – including bottles of e-liquid – is 20mg/ml. Anything above this is not legal.