If you're on LND and looking to create re-usable invoices for tipping you can create one on RTL

Step 1: Hit 'Create Invoice' button

Step 2: Put in the description and tip amount

Step 3: Set expiry for a long period. E.g. 100 day or whatever

Step 4: Select 'AMP Invoice'

And hit 'Create Invoice'

Boom you have a reusable invoice, which will not expire until the expiry timeout and can be paid over and over again (by LND nodes at this time)