Detour (walking tour app) is shutting down; existing members will lose access

I got this email from Detour today:

"Hello,

We're writing to let you know that Detour's technology and content has been sold to Bose.

The Detour app will continue to operate until May 31st (and all tours are now free), at which point it will shut down while Bose pursues new partners to host the Detour tours as part of its upcoming augmented reality platform.

Sincerely, The Detour Team"

I paid a one-off $19.99 for (non-time-limited) access to all their tours (or maybe just all their San Francisco tours; I don't recall). But now that they are shutting down, I will lose access to those, and no refund has been offered.