Most terms-of-service include a phrase the service can cancel for reasonable (sometimes for any) reason. Paying customers back is the easiest approach. For a ne

Most terms-of-service include a phrase the service can cancel for reasonable (sometimes for any) reason. Paying customers back is the easiest approach. For a new bootstrapped service that would be manageable (won't bankrupt you). As you said annual pre-payment is great but best to not spend it all immediately. Setting up a help page pointing to similar services would be nice. Example https://www.mapzen.com/blog/migration/ https://www.mapzen.com/blog/migration/ And with GDPR in mind a way to export data. Also privacy related make clear who now controls the existing data (you personally is fine, deleting all is fine, some users worry it gets sold). If you registered a company (UG, GmbH) then for tax purposes you might need to proper shutdown the company. There's processes and form for that and you might need to submit annual accounts for several years even if both income and expenses are zero. With German UG you're still personal liable should any customer demand money, let's say they sue for damaged and however unjustified you then have legal costs more than the company has on their bank account. GmbH costs 25000 Euro to setup so I assume with bootstrapping you don't go that route. When we were still bootstrapped companies flat out asked us how long we existed (e.g. 3 months) and what guarantee there is we still exist in 6 months. It's a stigma but people have been burned with startups in the past.