I am a DM who hosts a game once or twice a month for my friends and sometimes we don't manage to find a suitable time slot for our game for several weeks - so there are months with no game at all. I love syrinscape but a monthly subscription under these cirumstances just isn't worth it. I am totally ok with paying a fair amount for the work you have done, but please consider a one time payment. Maybe just with a "local" option, so you don't have to maintain the server space and check for proper licensing.
In fact I am just looking for a way to combine my own music with the other possibilities syrinscape has to offer. So maybe a "Sound Creator light" where you just can add some local music to Syrinscape would be sufficient. I am aware that under these circumstances the soundsets you created on one device are not transferred automatically to the other devices. But you have to have some trade-offs, when paying not the subscription.