For exploration licences you get 5 years. Year 3 requires 50% reduction, Year 4 another 50% reduction before relinquishment after year 5. - Unless you convert to a Prospecting or Mining Licence, but you need to have a resource.
Im not sure on the reason for dropping the tenements, but I can assure you that annual minimum expenditure is related to size, and TAM has (had) a huge landholding.
TAM Price at posting:
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