I just found this below on LexisNexis UK - quoted for the purposes of Criticism. Most important parts bolded. From BMS Computer Solutions v AB Agri
it looks to me that the revocability of a Perpetual licence depends heavily on the circumstances, as I thought.
Never ending or of indefinite duration?
The word ‘perpetual’ in a software licence can have different shades of meaning depending on the circumstances. It could mean:
never ending, ie incapable of being bought to an end, or
operating without a specific limit of time (ie of indefinite duration) but still ultimately terminable
In the case of BMS Computer Solutions v AB Agri
, the licence was initially for a ten-year term (subject to various provisions for early termination for breach, etc). The licence (and an associated software support agreement) were subsequently amended by a variation agreement to become a ‘perpetual licence’.
The case concerned the meaning of the word ‘perpetual’ in this context. The court held that the licence was ‘of indefinite duration, but subject to any contractual provisions governing termination of the licence’. The reasons for this decision depended on the circumstances
, in particular:
the variation agreement was not intended to wholly displace the earlier licence agreement, which meant the original termination provisions survived the variation. The licence had simply been varied from being one of limited (ten-year) duration to being of indefinite duration. The use of the word ‘perpetual’ did not implicitly terminate earlier termination provisions, and
there was clearly a continued commercial need for the termination provisions in the licence agreement to continue, otherwise there was no way of bringing potentially onerous obligations in that agreement (eg reporting obligations) to an end
This interpretation of ‘perpetual’ relied heavily on the facts of this case
and so a different interpretation could be reached in different circumstances
. Generally, it is good practice to avoid drafting intellectual property licences of ‘perpetual’ or indefinite duration as this leads to uncertainty and disputes. The better approach is for the parties to agree a specific duration and a clear basis to establish when the licence will expire or can be terminated. If the intention is that a licence will be never ending and not capable of termination then this should be expressly stated.
Where a perpetual licence includes an obligation to support and maintain the software in perpetuity, there is no implied right for the supplier to terminate. It is essential that the right to terminate is specified in the agreement.