Calculating a few thousand routes

I am trying to calculate the routes between around 6000 points in one layer, and 5 points in another layer.
I am unable to do so using the free API key, and it seems that API keys with higher limits on routes calculated in a day are no longer available.

So; 1. How to buy an API key with a higher limit? or 2. How do I calculate this amount of routes in another way?

Regards Oliver

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