Hello,
It's a pity to read that. First of all because it's disappointing for you who put much effort into creating templates and extensions; Second, because I appreciate quality, creativity and diversity, especially because there are lots of templates out there but many of them are quite much the same ...
Perhaps you should reconsider your subscription policy. Lifetime subscription for a cheap one-time payment is a good thing for customers, but obviously it's not profitable for you. In the end, the latter won't be a good thing for anyone of us.
So, I would either consider abandoning the lifetime subscription or, if you want to keep it, make it just one of several options and raise its price. I guess (at least many of) those who already have purchased a lifetime subscription would accept a change to recurring payments in order to get your business back on track. I think this would make sense both for you and for your customers.
Good luck,
Emanuel