We are a bar and people want to keep a tab open all evening. Does a bar POS here do that?

Yes, through tables. Add a few tables named Bar 1, Bar 2 and so on under Settings → Tables & QR ordering, and put them in an area called Bar. On the POS, tap the table to open a tab, add the drinks, and press Send to kitchen to record the round. Each new round goes on the same tab, and at the end you charge the whole tab or split it by item or evenly. A POS for a bar and restaurant needs exactly this, and it is the same floor your restaurant tables use. The Tables, tabs and the kitchen screen tab in the docs covers tabs and rounds.