Great question, would actually really like to know this details as well? Does anyone have an answer for this? Lets go DGPT, love this project. A good amount of 'big names' in the industry are behind it / have written reviews on it!
Let me see if I can get this answer from the team. Will get back to you guys.
Got a response from DigiPulse team. The service is priced in fiat and paid for in DGPT. Later on fiat payments will be possible.
Regarding the time period - it is based on the asset release timestamp update (ARTu). In short, if the user wants to update his activity in 2 weeks, then the payment happens every 2 weeks. If 3 months, then once every 3 months.
It is subscription based, but not tied to yearly or monthly
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Hopefully that is helpful!