Hi,
At the moment, there are no plans to implement a subscription license.
Because it's just a small business, I have a goal to keep the licensing as simple as possible. Multiple licensing systems would make maintaining sales channels much more time consuming, and I don't want to move away from the current system as I feel it is more ethical to allow people to continue to use things that they've bought. I know that subscription licenses are fast becoming the norm for software licensing, but I would prefer to sell licenses based on continuous improvement to the product rather than a 'lock in' factor.