Depending on your subscription plan, you can have a limit of 50 (Starter), 250 (Starter+) or 500 (Regular), 1500 Orders per Route Plan. That is the maximum number of Orders you can optimize at the same time in the same Route Plan.
With a Regular Account you can build unlimited Route Plans for up to 500 Orders EACH, no matter how many Drivers you assign. This means that if you build routes for one Driver only, you can assign up to 500 stops per Route Plan to this Driver.
In case of multi-vehicle planning, instead, 500 is the total number of Orders your Drivers can collectively serve IN A SINGLE ROUTE PLAN.
Remember again that you can create unlimited Route Plans, so do not worry if you have more than 500 customers. Unless you need to serve them all in the same Route Plan (on the same day, for instance), the Regular account will be fine (you could serve 500 Orders on Monday, 500 different Orders on Tuesday and so forth).
Anyway, if you need to build larger Route Plans, contact us to get a quote.